More than 50 people were crushed to death Tuesday at the funeral of an Iranian general in the southeastern city of Kerman, Iranian media reported, citing a morgue count.
The tragedy left 212 people injured, a small number of whom were in a serious condition, semi-official news agency ISNA added, citing Kerman's emergency services chief Mohammad Saberi.
The injured were immediately transferred to hospital.
AFP correspondents in Kerman said the streets were packed with mourners, while others took refuge on hillsides around the city.
Soleimani, the head of the Guards' Quds Force foreign operations arm, was assassinated on Friday in a US strike near Baghdad international airport, an operation that shocked Iran.
"The enemy killed him unjustly," the Revolutionary Guards' top commander, Major General Hossein Salami said, adding the process of "expelling the United States from the region has begun".
"Our will is firm. We also tell our enemies that we will take revenge, and that if they (strike again) we will set fire to what they love," he told the sea of black-clad mourners.
"They themselves know well what places I am talking about."
Schoolgirls joined chants of "Death to Trump" from the crowd, an AFP correspondent reported.
Tuesday's funeral comes after days of processions through the southwestern city of Ahvaz and the shrine cities of Qom and Mashhad as well as the capital Tehran.
The assassination of Soleimani set off an escalating war of words between Iran and the United States.
In Tehran, President Hassan Rouhani on Monday warned Trump to "never threaten" Iran, after the US leader issued a US strike list of 52 targets in the Islamic republic.
On Tuesday, Iranian lawmakers voted to designate all US forces around the world "terrorists" over Soleimani's killing.
Parliament also agreed to bolster the coffers of the Quds Force, which Soleimani led, by $244 million (200 million euros).
In Kerman, people converged from afar on Azadi Square where two flag-draped coffins were on display, with the second one reportedly containing the remains of Soleimani's closest aide, Brigadier General Hossein Pourjafari.
"We're here today to pay respects to the great commander of the holy defence," said one of the mourners who came from the southern city of Shiraz to attend the funeral in Kerman.
"Haj Qasem was not only loved in Kerman, or Iran, but also the whole world," Hemmat Dehghan told AFP.
"The security of the whole world, Muslims, Shiites, Iraq, Syria, Afghanistan and especially Iran, all owe it to him," said the 56-year-old war veteran.
Another mourner said Soleimani's assassination "boils the blood of the Iranian people".
"He was seen as a great man who was ready to serve his people both then in the war and now. He must certainly be avenged," said Sara Khaksar, an 18-year-old student.
Friday's assassination of the 62-year-old Soleimani heightened international concern about a new war in the volatile Middle East.
Iraq's parliament has demanded the government expel the 5,200 American troops stationed in the country in response to the drone attack which also killed top Iraqi military figure Abu Mahdi al-Muhandis.
Baghdad requested in a letter to the UN—seen by AFP—that the Security Council condemn the US strike so that "the law of the jungle" is not allowed to prevail.
The operation represented "a dangerous escalation that could lead to a devastating war in Iraq, the region and the world," wrote Iraq's UN ambassador Mohammed Hussein Bahr-Aluloom.
On Sunday night, the US mistakenly notified the Iraq of an imminent troop pullout in a letter that sparked confusion in Washington.
"We respect your sovereign decision to order our departure," said the letter, whose authenticity was confirmed to AFP by both Iraqi and US defence officials.
In the letter, US Brigadier General William Seely said the US-led coalition would "be repositioning forces".
But Pentagon Joint Chiefs Chairman Mark Milley said the letter was a mere "draft" that was sent by mistake.
Germany said Tuesday it was withdrawing some of its troops deployed as the anti-IS coalition in Iraq.
NATO chief Jens Stoltenberg warned on Monday that Iran must avoid "further violence and provocations".
The European Union, whose foreign ministers will hold emergency talks on the crisis Friday, said it was in both Iran and Iraq's interests to "take the path of sobriety and not the path of escalation".
Saudi Arabia -- an oil-rich US ally seen as vulnerable to Iranian counter strikes—also appealed for calm after a "very dangerous" escalation.
World financial markets have been on edge over the crisis.
"The new year has started with a bang in so far as volatility is concerned," said Fawad Razaqzada at Forex.com.
"This is mainly due to the escalation of tensions between the US and Iran after Trump ordered the assassination of Iranian military commander Qasem Soleimani."
Soleimani is expected to be buried at the martyrs' cemetery in Kerman between 2:00 and 4:00 pm (1030 and 1230 GMT).