Kamal Kharrazi, an adviser to Iran's supreme leader, said Thursday that Tehran has not closed all doors to resolve its disputes with the United States and is ready for indirect negotiations with Washington.

Tehran has so far rebuffed President Donald Trump's warning it to make a deal or face military consequences. Supreme Leader Ayatollah Ali Khamenei called the message deceptive and Foreign Minister Abbas Araqchi said talks are impossible unless Washington changes its "maximum pressure" policy.

"The Islamic Republic has not closed all doors. It is ready for indirect negotiations with the United States in order to evaluate the other party, state its own conditions and make the appropriate decision," Kharrazi said, according to the semi-official Iranian Students News Agency.

Iran is meant to soon reply to Trump's letter, with Araqchi saying last week Tehran would take into consideration both Trump's threat and opportunities in its response.

In his first 2017-21 term, Trump withdrew the U.S. from a 2015 deal between Iran and world powers that placed strict limits on Tehran's disputed nuclear activities in exchange for sanctions relief.

After Trump pulled out in 2018 and reimposed sweeping U.S. sanctions, the Islamic Republic breached and has since far surpassed those limits in its escalating program of uranium enrichment.

Western powers accuse Iran of having an clandestine agenda to develop nuclear weapons capability by enriching uranium to a high level of fissile purity, above what they say is justifiable for a civilian atomic energy program.

Tehran says its nuclear program is wholly for civilian energy purposes.