President Trump told Chinese President Xi Jinping during their closely watched summit in Washington, DC, to stop supporting Iran in its war against the US, according to a US official.

US Ambassador David Perdue told CNBC on Friday that Trump informed Xi any direct — or indirect — support for Tehran was “totally unacceptable.”

“We have made it very clear to them weeks ago that any help that they would give Iran, whether it be direct or indirect, whether it be intelligence or parts or military equipment, was totally unacceptable. President Trump made that very clear again yesterday,” Perdue said in an interview.

Asked by reporters at the White House, Trump affirmed he “did” make that clear in his Thursday meeting with China’s leader.

China has provided Iran both economic support, in the form of buying up 90% of Iran’s oil exports, and intelligence support, in the form of reportedly supplying satellite images earlier this month of an air base in Jordan before and after a deadly missile strike that killed three US service members.

“They basically do what we do,” Trump said when asked on Air Force One about the Wall Street Journal report. “When they say China spies on us, I say, ‘You’re right, and we spy on them too.’”

On Friday, Perdue noted progress: “We have seen evidence that they have listened to us,” he said.

“They pulled some things down,” Perdue added, noting: “We have evidence they pay attention when President Trump speaks about Iran.”

The warning came after US special envoys Jared Kushner and Steve Witkoff held meetings with Iranian officials on the sidelines of the United Nations General Assembly that have reportedly resulted in a new purported peace proposal to be carried out in phases, according to Reuters and Bloomberg.

The first phase would end the US naval blockade of Iranian ports in exchange for the reopening of the Strait of Hormuz.

A US official said Friday that “positive and constructive discussions through the mediators” were occurring — without confirming the exact outlines of the peace proposal.

“The United States is in a very strong position with control of the Strait of Hormuz, so we are not in a rush,” the official added.

Almost 40 million barrels of oil have also passed through the strait in the past 48 hours, the official noted, suggesting Iran’s grip on the critical energy chokepoint may be slipping.