Iran's supreme leader mocked America's presidential election on Tuesday in a televised address, quoting US President Donald Trump's own baseless claims about voter fraud to criticise the vote as Tehran marked the 1979 US Embassy hostage crisis.

Ayatollah Ali Khamenei reiterated a long standing Iranian position that it didn't matter whether Trump or Joe Biden wins the vote, but the stakes couldn't be higher for the Islamic Republic.

Another four years could see Trump's maximum pressure campaigns further expand as it crushes the Iranian economy and stops Tehran from openly selling its crude oil abroad.

Meanwhile, Biden has said he would consider re-entering Tehran's 2015 nuclear deal with world powers, providing possible relief to the beleaguered Iranian rial.

"If you look at their own situation, it's lovely to watch. The incumbent president, who is supposed to hold the elections, says this is the most-rigged US election throughout history,” Khamenei said, not acknowledging that individual US states run the vote.

“Who says this? The sitting president who is arranging the elections himself. His opponent says Trump intends to widely cheat. This is American democracy."

Khamenei added that the result of the vote “is none of our business, meaning it won't influence our policy at all".

"Our policy is clear and well-calculated and people coming and going will have no impact on it."

Khamenei, 81, as supreme leader has final say on all matters of state in Iran. He approved the efforts at reaching the nuclear deal, which saw Iran agree to limit its enrichment of uranium in exchange for the lifting of economic sanctions.

But Trump withdrew from the deal in 2018, complaining it didn't address Iran's ballistic missile programme nor its regional policies. Iran later withdrew from all the deal's limits, though Tehran still allows UN inspectors access to nuclear sites.

Satellite photos show it is now starting new construction work at its Natanz nuclear site, which was targeted in a reported sabotage attack in July.

Khamenei spoke as the coronavirus pandemic forced authorities to cancel a planned commemoration of the November 4, 1979 takeover of the US Embassy in Tehran. That started a 444-day hostage crisis that transfixed America and still affects relations between Washington and Iran today.

Anti-Americanism remains a cornerstone of Iranian policy, over four decades after the takeover.

"Such an empire will not last long. Its obvious that when a regime reaches this point, it will not live for much longer and will be destroyed,” Khamenei said of America.

“Of course, some of them if they take office will destroy America sooner, and some others if elected will cause America to be destroyed a bit later.”