(COMBO) This combination of pictures shows US President Donald Trump and Iran's Supreme Leader Ayatollah Ali Khamenei. AFP
"The letter has not reached us yet but an envoy from an Arab country is set to deliver it soon in Tehran," Foreign Minister Abbas Araghchi told reporters after a cabinet meeting.
He did not elaborate on the identity of the Arab country or the timing of the letter's delivery.
On Friday, Trump said he wrote a letter to Iran's supreme leader Ayatollah Ali Khamenei calling for talks to forge a new deal on Tehran's nuclear programme, or face a potential military option.
But Iran has rejected talks under "maximum pressure" policy that Trump reinstated after his return to the White House in January.
Under the policy, Trump pulled out of Iran's nuclear accord in 2018 and reimposed sweeping sanctions on Tehran and imposed new ones.
In February, Khamenei urged the government not to negotiate with the United States, citing Washington's withdrawal from the nuclear deal.
Last week he also slammed "bullying" tactics by some governments that insist on negotiations that "are not aimed at solving problems," but at "domination".
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