Iran is accusing US Secretary of State Rex Tillerson of “a brazen interventionist plan” to change the current government that violates international law and the UN Charter.

Iran's UN Ambassador Gholamali Khoshroo said in a letter to Secretary-General Antonio Guterres, circulated Tuesday, that Tillerson's comments are also “a flagrant violation” of the 1981 Algiers Accords in which the United States pledged “not to intervene, directly or indirectly, politically or militarily, in Iran's internal affairs.”

Tillerson said in a June 14 hearing before the House Foreign Affairs Committee on the 2018 State Department budget that US policy is to prevent Iran from developing nuclear weapons “and work toward support of those elements inside of Iran that would lead to a peaceful transition of that government.”

“Those elements are there, certainly as we know,” he said.

Kohshroo said Iran expects all countries to condemn “such grotesque policy statements and advise the government of the United States to act responsibly and to adhere to the principles of the (UN) Charter and international law.”

He noted that Tillerson's comments came weeks after President Hassan Rouhani's re-election to another four-year term and local elections in which 71 per cent of the Iranian people participated.

Rouhani is a political moderate who defeated a hardline opponent.

“The people of Iran have repeatedly proven that they are the ones to decide their own destiny and thus attempts by the United States to interfere in Iranian domestic affairs will be doomed to failure,” Kohshroo said.

“They have learned how to stand strong and independent, as demonstrated in the Islamic Revolution of 1979.”

He said Tillerson's statement also coincided with the released of newly declassified documents that “further clarified how United States agencies were behind the overthrow of Mohammad Mossadegh, the popular and democratically elected prime minister of Iran on Aug 19, 1953.”

At the June 14 hearing, Tillerson said the Trump administration's Iranian policy is under development. “But I would tell you that we certainly recognise Iran's continued destabilising (role) in the region,” Tillerson said, citing its payment of foreign fighters, support for Hezbollah extremists, and “their export of militia forces in Syria, in Iraq, in Yemen.”

US lawmakers have long sought to hit Iran with more sanctions in order to check its ballistic missile program and rebuke Tehran's continued support for terrorist groups, and on June 15 the Senate approved a sweeping sanctions bill.

The bill imposes mandatory sanctions on people involved in Iran's ballistic missile program and anyone who does business with them. The measure also would apply terrorism sanctions to the country's Revolutionary Guards and enforce an arms embargo. It now goes to the House.

Senators insisted the new Iran sanctions won't undermine or impede enforcement of the landmark nuclear deal that former president Barack Obama and five other key nations reached with Tehran two years ago.