In his first public remarks on the unrest, Iran’s supreme leader blamed the US and Israel for the anti-government rallies sweeping the nation.
Ayatollah Ali Khamenei claimed that Qurans had been destroyed and said that “riots” had been “manufactured” by Iran’s fiercest foes and friends.
Additionally, he urged security forces to be prepared to handle any future unrest.
The protests – the biggest challenge to his rule for a decade – were sparked by the death in custody of a woman.
Mahsa Amini, 22, fell into a coma hours after being detained by morality police on 13 September in Tehran for allegedly breaking the strict law requiring women to cover their hair with a hijab, or headscarf. She died three days later.
Her family has alleged that officers beat her head with a baton and banged her head against one of their vehicles. The police have said there is no evidence of any mistreatment and that she suffered “sudden heart failure”.
Women have led the protests that began after Ms Amini’s funeral, waving their headscarves in the air or setting them on fire to chants of “Woman, life, freedom” and “Death to the dictator” – a reference to Ayatollah Khamenei.
After unrest at many universities, school protests are now spreading in Iran. In Shiraz, schoolgirls wave their head coverings in the air today chanting “death to the dictator” on day 18 of protests over the death of #MahsaAmini.#مهسا_امینیpic.twitter.com/rCIhihzR7U
— Shayan Sardarizadeh (@Shayan86) October 3, 2022
Iranian schoolgirls remove their head coverings and chant “mullahs must go away” today, on day 18 of protests over the death of #MahsaAmini in morality police custody for “improper hijab” amid mass arrests of activists and an internet shutdown.#مهسا_امینیpic.twitter.com/a01ILrgOlS
— Shayan Sardarizadeh (@Shayan86) October 3, 2022
Addressing a graduation ceremony of police and armed forces cadets on Monday, the supreme leader said Ms Amini’s death “broke our hearts”.
“But what is not normal is that some people, without proof or an investigation, have made the streets dangerous, burned the Quran, removed hijabs from veiled women and set fire to mosques and cars,” he added, without mentioning any specific incidents.
The ayatollah, who has the final say on all state matters, asserted that foreign powers had planned “rioting” because they could not tolerate Iran “attaining strength in all spheres”.
“I say clearly that these riots and the insecurity were engineered by America and the occupying, false Zionist regime [Israel], as well as their paid agents, with the help of some traitorous Iranians abroad.”
He also gave his full backing to the security forces, saying that they had faced “injustice” during the unrest.
Iran Human Rights, a Norway-based group, said on Sunday that at least 133 people had been killed by security forces so far. They include 41 protesters whom ethnic Baluch activists said had died in clashes in Zahedan on Friday.
State media have reported that more than 40 people have been killed,including security personnel.
Ayatollah Khamenei’s comments came a day after security forces violently cracked down on a protest by students at Iran’s most prestigious science and engineering university, reportedly arresting dozens.
The BBC’s Kasra Naji says the gunfire heard around the campus of Sharif University of Technology in Tehran on Sunday night spread fear among many Iranians that authorities had decided to make an example of the students.
Security forces tried to the enter the campus, but the students drove them back and closed all the entrance gates.
But, our correspondent adds, a siege developed and the students who tried to leave through an adjacent car park were picked up one by one and beaten, blindfolded and taken away.
In one video posted on social media, a large number of people are seen running inside a car park while being pursued by men on motorbikes.
Breaking: #Iran security forces have laid siege to #Sharif university of Tehran. Many students and professors have been beaten up, some students are entrapped inside. The security forces are rounding up students. Shots can be heard in these videos… #MahsaAmini pic.twitter.com/gx9Bugu4ea
— Rana Rahimpour (@ranarahimpour) October 2, 2022
The siege was lifted later in the night following the intervention of professors and a government minister.
On Monday, students at the university announced that they would not go back to classes until all of their fellow students had been released from detention. The university meanwhile said it had moved classes online, citing “the need to protect students”.
Protests were also reported at several otheruniversities around the country.