A eulogist at the funeral procession for Major General Qassem Soleimani called for a US$80 million (NZ$120 million) bounty to be placed on US President Donald Trump's head.
The announcement by the eulogist was broadcast live from Mashhad on state television as millions of people took to the street for Soleimani's funeral.
The former head of Iran's elite Quds Force was killed in a targeted airstrike by the US at Baghdad International Airport.
"We are 80 million Iranians," the eulogist said, referencing the country's population.
"If each one of us puts aside one American dollar, we will have 80 million American dollars, and we will reward anyone who brings us [Trump]'s head with that amount."
There was confusion as to the source of the bounty after M. Hanif Jazayeri, a news editor affiliated with the National Council of Resistance in Iran, claimed "Iran's regime" had announced it.
An article by Heavy said this was "misleading" because it was the eulogist who made the announcement and not state TV. It was, however, broadcast on state TV.
Another speaker in Mashhad also told the crowd they will see "the uprooting of the US" in the region.
"You crazy, yellow-haired man [Trump]! Listen carefully! 'Down with the US' ... You Israelis! We will send you death ... every single drop of our tears will turn into a missile into your land," he said.
Tensions between the US and Iran spiked in late December after an American contractor was killed in Iraq. US officials blamed Iranian-backed militia Kata'ib Hezbollah for the attack and subsequently carried out military strikes against the militia, killing at least 25 fighters.
That retaliation by the US triggered protests in the streets of Iraq and an attack on the US embassy in Baghdad, which the US blamed on Iranian-backed militia.
The killing of Soleimani was then carried out as a response to that embassy attack.
Iranian MP Abolfazl Abutorabi threatened to launch an attack on the White House in retaliation to the airstrike on Saturday.
His threat was made during an open session of parliament in Tehran after Trump warned that the US would hit 52 Iranian sites that are "important" to Iran and its culture.
"We can attack the White House itself, we can respond to them on the American soil. We have the power, and God willing we will respond in an appropriate time," Abutorabi said, according to Iranian news agency ILNA.
International correspondent for The Independent Borzou Daragahi said Abutorabi is an obscure lawmaker known for making provocative statements, and what he said should be viewed with scepticism.
Daragahi added Iran isn't believed to have any missiles that could reach Washington D.C., and an individual suicide attack would likely be the only realistic way to reach the White House.