Iran has asked the United Nations to push back against Washington's recent decision to impose sanctions on Foreign Minister Mohammad Javad Zarif, a move that came amid heightened tensions between the two countries.
Iran's UN ambassador called the American sanctions a "brazen violation of the fundamental principles of international law" in a letter to UN Secretary-General Antonio Guterres, Reuters reported on Tuesday.
Majid Takht Ravanchi urged the international community to condemn the measure, the news agency said.
"Coercing nations into complying with the United States' illegal demands threatens multilateralism, as the foundation of international relations, and sets a dangerous precedent, paving the way for those who aspire to rather divide, not unite, nations," he wrote.
Donald Trump's administration imposed sanctions on Zarif last week, accusing the senior Iranian diplomat of acting on behalf of Iran's Supreme Leader Ali Khamenei, who is also under American sanctions.
"The United States is sending a clear message to the Iranian regime that its recent behaviour is completely unacceptable," US Treasury Secretary Steve Mnuchin said at the time.
Zarif responded to the news on Twitter, saying the sanctions would have "no effect" on him or his family, as he has "no property or interests outside of Iran".
"Thank you for considering me such a huge threat to your agenda," he tweeted.
'Maximum restraint'
Zarif and other Iranian leaders have remained defiant in the face of the Trump administration's ongoing "maximum pressure" campaign against the country.
Last year, the US president withdrew from a landmark 2015 nuclear deal under which Tehran agreed to curb its nuclear programme in exchange for a lifting of international sanctions.
The US has since reimposed a series of harsh economic measures targeting key Iranian industries and individuals - moves that have not only drawn the ire of Iran's government, but also led to tensions with European countries that remain committed to the nuclear accord.
Washington has also accused Tehran of being responsible for a series of attacks in the Gulf region - accusations that Iranian officials have repeatedly denied.
The heightened tensions between Iran and the US have caused alarm internationally, with countries, rights groups and political observers urging both sides to maintain calm and avoid a direct confrontation.
In his letter to Guterres, Iran's envoy to the UN urged the secretary-general to play an "active role in preserving the integrity of the [UN] in line with your responsibility to counter the current dangerous trend".
It is not clear what Guterres could do, however, Reuters reported.
UN spokesman Stephane Dujarric also declined to comment on the letter, the news agency said.
"When I ask for maximum restraint, I ask for maximum restraint at all levels," Dujarric told reporters, when asked about the US sanctions against Zarif.
Meanwhile on Tuesday, Iranian President Hassan Rouhani said his government was open to negotiations with the US - but only if Washington agrees to lift its sanctions against the country.
In response to US pressure, Iran has begun scaling back various commitments it made as part of the 2015 nuclear deal, while urging European countries - namely France, Germany and Britain - to protect it from the sanctions.
"Peace with Iran is the mother of all peace, war with Iran is the mother of all wars," Rouhani said during a speech at the country's foreign ministry, as reported by Reuters.
The president added that Iran especially wants to be able to export its oil - a key sector of the Iranian economy that was hit by renewed US sanctions last autumn.
His comments came after Zarif said on Monday that he was sanctioned after he turned down an invitation to hold talks with Trump at the White House.
"I also said that while @realdonaldtrump may want photo op, the US isn't interested in talks; rather, Iran's submission. That will never happen," Zarif wrote on Twitter.
