UNITED NATIONS — The United States announced new economic penalties against Iran’s largest oil customer on Wednesday, further squeezing the country as its president told the United Nations he would not negotiate with an “enemy who uses sanction and poverty as a tool.”
The actions and statements by both countries appeared to rule out what would be a historic meeting between President Trump and President Hassan Rouhani of Iran at the United Nations, where both leaders were attending the General Assembly.
Secretary of State Mike Pompeo said the additional American sanctions would punish “certain Chinese entities for knowingly transporting oil from Iran” in defiance of American financial restrictions imposed earlier this year. Mr. Pompeo also said that economic punishments would be imposed against executives of Chinese companies importing Iran’s oil.
China has been the biggest foreign buyer of Iran’s oil, a crucial Iranian export. Last year, roughly 6 percent of China’s oil imports came from Iran.
But in the last two months, Chinese state-owned companies have begun importing more oil from Saudi Arabia under tightening pressure from the Trump administration to choke Iran’s economy and force Tehran into new negotiations to limit its nuclear and military programs.
Mr. Pompeo’s comments came at a meeting near the United Nations headquarters in New York, where diplomats were scrambling to set up a meeting between Mr. Trump and Mr. Rouhani.
Both sides have previously appeared willing to talk, but Iran has insisted that the United States must first ease its sanctions — which Mr. Pompeo made clear again on Wednesday would not happen.
Mr. Rouhani rejected any meeting if the sanctions were not eased. In his speech at the General Assembly on Wednesday, Mr. Rouhani devoted considerable time to berating the Trump administration for inviting him to talk while threatening Iran.
The Iranian response was “no, not under sanctions,” Mr. Rouhani said. “We will never meet with an enemy that uses sanction and poverty as a tool.”
Referring to Mr. Trump’s repudiation of the 2015 nuclear accord that eased sanctions in return for curbs on Iran’s nuclear activities, Mr. Rouhani said: “If you want a ‘yes’ response then the only road to negotiations is returning to your commitments.”
“A photo opportunity is the last stop, not the first stop,” he said of meeting Mr. Trump.
Mr. Pompeo announced the sanctions during a speech at a conference sponsored by United Against Nuclear Iran — an advocacy group that Tehran this week declared a terrorist organization. He appeared to taunt Iran’s “panicked aggression” in the wake of the American pressure campaign that has weakened its economy.
He said Iran’s leaders respond to “strength and not to supplication” and drew titters from the audience when he noted that Mr. Rouhani had claimed of working to bring peace to the Middle East.
“They’re calling every play in their playbook to goad us into conflict, to create division among nations, and extort them into action,” Mr. Pompeo said. “And you should know their playbook won’t succeed.”
Ali Rabiei, a spokesman for Mr. Rouhani, described an overnight flurry of messages between Iranian and European officials about a possible meeting on Wednesday with Mr. Trump at the United Nations.
However, Mr. Rabiei told Iranian media, such a meeting would only happen if it included leaders and diplomats from other world powers, and if the United States appeared willing to return to the nuclear accord.
Federica Mogherini, the European Union’s foreign policy chief, predicted it would be difficult to save the nuclear deal. But, she said, Iran could easily return to compliance — including by stopping its uranium enrichment.
“We all welcome the efforts being made to open the channel of dialogue,” Ms. Mogherini said Wednesday of the possibility of talks between the United States and Iran. Her comments followed a meeting of the nations still party to the nuclear accord — Britain, China, France, Germany, Iran and Russia — where she said all committed to try to preserve it.
Iran’s foreign minister, Mohammad Javad Zarif, described it as “a good meeting” but declined further comment.
In Iran, hard-line members of the hierarchy who are especially suspicious of the Americans welcomed Mr. Rouhani’s rejection of Mr. Trump’s invitation.
“If such a thing happens Messrs Rouhani and Zarif must know they will pay a very high price,” said Javad Karimi Ghodoosi, a member of Parliament.
President Emmanuel Macron of France has for weeks sought to broker talks between the United States and Iran on the sidelines of the General Assembly meetings, and met with Mr. Trump on Wednesday. In a statement, the White House said the two presidents had “discussed ways to address tensions in the Middle East, particularly in responding to Iran’s increasingly belligerent behavior.”
In his speech, Mr. Pompeo again accused Iran of bombing four oil tankers in the Persian Gulf in May, downing an unmanned American spy drone in June and attacking oil fields in Saudi Arabia this month as evidence of its “long history of unprovoked aggression.”
Iran has denied responsibility for the Sept. 14 strikes on the Saudi oil facilities, which Mr. Pompeo has called an “act of war” and which again raised the specter of a new military conflict in the Middle East. Officials in the Gulf also blamed Iran for the attacks but urged caution, and not until this week did diplomats from Britain, France and Germany publicly agree that they considered Tehran responsible for the strikes.
“Thank God our European allies, two days ago, returned to our side,” former Senator Joseph I. Lieberman, the chairman of United Against Nuclear Iran, who was the Democratic Party’s vice-presidential nominee in 2000, said on Wednesday as he introduced Mr. Pompeo at the conference. “And together now, hopefully, we will move forward.”
In July, the State Department announced its first set of Iran-related sanctions against a Chinese oil company, Zhuhai Zhenrong and its chief executive, Li Youmin.
But the United States has avoided sanctioning Chinese banks or Sinopec, a much larger state-owned company that is also a big importer of Iranian oil. Sanctions on those institutions would have far-reaching effects in global finance and business.
Mr. Pompeo also said the United States would intensify warnings to countries and companies against doing business with entities linked to the Islamic Revolutionary Guards Corps, a branch of Iran’s military. The United States declared the Guards Corps a terrorist organization earlier this year; the broad designation prohibits doing business with as many as 11 million Iranians and affiliated groups.
The new warnings would work to “disentangle” legitimate business dealings from those with the Guards Corps, Mr. Pompeo said.
“This is the beginning of an awakening to the truth that Iran is the aggressor and not the aggrieved, as they claim,” Mr. Pompeo said.
The developments at the United Nations were unfolding as the fate of a Swedish-owned, British-flagged oil tanker, the Steno Impero, detained in Iran for months, remained unclear two days after the Iranians said the ship was free to leave.
An Iranian official on Wednesday said that while the detention order on the ship had been lifted, it may not leave Iran because of a pending inquiry into the ship’s conduct. The official, Seyed Abbas Mousavi, Iran’s Foreign Ministry spokesman, said on Twitter that “the investigation of some of its violations and environmental damage remains open.”
The ship has not budged from the southern Iranian port of Bandar Abbas. Iran detained the Stena Impero on July 19 and accused it of having violated maritime regulations in the Strait of Hormuz, a main passageway for the world’s oil supply. But the seizure was widely seen as retaliation for the earlier detention of an Iranian vessel, the Grace 1, later renamed the Adrian Darya, in Gibraltar. That vessel was released in August.