The United States has no right to trigger the reimposition of all UN sanctions on Iran, the Iranian foreign minister said in a letter to the United Nations, calling on Security Council members to reject Washington's move.

"The US push to reimpose UN sanctions on Iran will have dangerous consequences ... Iran has exercised restraint in good faith ... Now it is the international community's turn to counter the unlawful push by the United States," Javad Zarif said in the letter.

Iranian state TV said the letter was sent to the head of the UN Security Council by Iran's UN envoy Majid Takhteravanchi.

US Secretary of State Mike Pompeo said on Wednesday that US President Donald Trump has directed him to trigger the 'snapback' of all UN sanctions on Iran at the Security Council in New York on Thursday.

In a bid to reimpose the sanctions, the United States will submit a complaint to the 15-member body about Iran's non-compliance with a 2015 agreement on its nuclear program, even though Washington quit the accord in 2018.

Zarif said Washington had no right to trigger the snapback mechanism as it was no longer a party to the pact.

Russia backed up the Iranian stance.

Russia's UN ambassador rejected US plans to restore UN sanctions on Iran as "nonexistent," saying only a country that remains in the 2015 agreement can trigger the return of the sanctions in a process known informally as "snapback."

"We will not take it as snapback," Russian UN Ambassador Vassily Nebenzia told reporters, rejecting Pompeo's expected announcement.

"He's not triggering a snapback. Snapback can be triggered by a country that is a participant of the JCPOA, which the US is not," he said, referring to the accord by its formal name, the Joint Comprehensive Plan of Action (JCPOA).

"We consider snapback as nonexistent. We will not take it as a snapback," Nebenzia added.

When asked if Russia would reimpose UN sanctions on Iran, the Russian ambassador replied: "How can Russia reimpose UN sanctions on Iran if the resolution 2231 continues?"

He was referring to the UN Security Council resolution that enshrined the nuclear deal between Iran and six major powers: Britain, China, France, Germany, Russia and the United States.

That deal aimed to prevent Iran from developing nuclear weapons by restricting its atomic activities in return for wide relief from economic sanctions.