An Iranian politician has announced a USD$3 million ($A4.4 million) reward to "whoever kills Trump", Iranian semi-official News agency reports.

"On behalf of people of Kerman province, we will pay (a) three million dollar ($A4.4 million) award in cash to whoever kills Trump," Ahmad Hamzeh told parliamentarians, according to ISNA.

He did not elaborate whether it was a decision made by Iran's clerical rulers to threaten US President Donald Trump.

An Iranian MP has reportedly issued a bounty kill order for US President Donald Trump in light of a strike that killed one of the nation's top generals. (EPA)

Kerman is the hometown of Qassem Soleimani, Iran's top commander of the Quds Force who was killed by a US drone on January 3 in Iraq.

The announcement comes just a day after a leaked recording of the US President at a Republican Party donor's event revealed him detailling aspects of the strikes that killed Soleimani, which exacerbated tensions in the region.

In his speech — held inside the gilded ballroom on his Mar-a-Lago property — he claimed that Soleimani was "saying bad things about our country" before the strike, which led to his decision to authorise his killing.

Trump did not describe an "imminent threat" that led to his decision to kill Soleimani, the justification used by administration officials in the aftermath of the attack.

Instead, he described Soleimani as a "noted terrorist" who "was down on our list" and "was supposed to be in his country" before traveling to other nations in the region.