The commander of Iran's Islamic Revolutionary Guard Corps, Hossein Salami, told protesters that Saturday would be their last day of taking to the streets.
"Do not come to the streets! Today is the last day of the riots," he said in some of the toughest language used in the crisis, which Iran's clerical leadership blames on its foreign enemies including Israel and the US.
"This sinister plan is a plan hatched in the White House and the Zionist regime," Gen Salami said.
The widely feared Revolutionary Guards, who report directly to Supreme Leader Ayatollah Ali Khamenei, have not been deployed since demonstrations began on September 16. They are an elite force with a track record of crushing dissent.
Rights groups have said at least 250 protesters have been killed and thousands arrested across Iran in the protests, which have turned into a popular revolt by Iranians from all layers of society.
Iran has been gripped by protests since the death of 22-year-old Kurdish woman Mahsa Amini while in the custody of the morality police last month.
On Friday, video footage on social media showed protesters calling for the death of Ayatollah Khamenei and the Basij militia, which has played a major role in the crackdown on demonstrators.
The Intelligence Ministry and the intelligence arm of the Revolutionary Guards have accused spy agencies from the US, Britain, Israel and Saudi Arabia of having orchestrated the unrest to destabilise the Islamic Republic.
Gen Salami, who was speaking at a funeral of victims killed in an attack this week claimed by ISIS, reiterated that message in a direct address to the protesters.
"Don't sell your honour to America and don't slap the security forces who are defending you in the face," he said.
The IRGC commander's comments came at the funeral of victims of a deadly assault on a shrine in the southern Iranian city of Shiraz.
Mourners chanted slogans against nationwide "riots" over Mahsa Amini's death.
At least 15 people were killed on Wednesday at a key Shiite Muslim shrine in the city, according to official media, in an attack claimed by ISIS.
The shooting at the Shah Cheragh mausoleum came on the same day that thousands of people across Iran paid tribute to Amini, 40 days after her death in police custody.
Remarks made on Thursday by Iran's President Ebrahim Raisi appeared to link the Shiraz attack, one of the country's deadliest in years, with the protests and "riots" following Amini's death.
"The intention of the enemy is to disrupt the country's progress, and then these riots pave the ground for terrorist acts," he said in televised remarks.
During Saturday's funeral processions in Iran, the crowd also chanted slogans condemning the US, Israel and Britain for allegedly being "behind the riots", according to live footage broadcast on state television.
Brandishing Shiite symbols, the crowd marched through central Shiraz following a vehicle carrying the victims' coffins which were draped in the Iranian flag.
The crowd can be heard chanting "Death to America, to Israel, to England" and "The vigilant revolutionary people hates the rioters."
Meanwhile, the human rights group Hengaw reported security forces shot students at a girls' school in the city of Saqez. In another post, it said security forces opened fire on students at the Kurdistan University of Medical Science, in the Kurdistan provincial capital of Sanandaj.
Several students were injured, one of them shot in the head, Hengaw said.
