Iran’s president warned on Sunday that any US strike would trigger a “harsh response” from Tehran after an Iranian official in the region said at least 5,000 people — including about 500 security personnel — had been killed in nationwide protests.

Iran’s protests, sparked last month in Tehran’s Grand Bazaar over economic grievances, swiftly turned political and spread nationwide, drawing participants from across generations and income groups - shopkeepers, students, men and women, the poor and the well‑off - calling for the end of clerical rule.

US President Donald Trump has repeatedly threatened to intervene if protesters continued to be killed on the streets or were executed.

He said in an interview with Politico on Saturday: “It’s time to look for new leadership in Iran”.

Iran indicated on Sunday it might go ahead with the execution of people detained during the unrest, and with its clerical rulers facing mounting international pressure over the bloodiest unrest since the 1979 Islamic revolution, is seeking to deter Trump from stepping in.

Iran’s President Masoud Pezeshkian on X warned that Tehran’s response “to any unjust aggression will be harsh and regrettable”, adding that any attack on the country’s supreme leader is “tantamount to an all-out war against the nation”.

Protests dwindled last week following a violent crackdown.

US-based rights group HRANA said on Saturday the death toll had reached 3,308, with another 4,382 cases under review.

It said it had confirmed more than 24,000 arrests.

On Friday, Trump thanked Tehran’s leaders in a social media post, saying they had called off scheduled executions of 800 people.

He has moved US military assets into the region but has not specified what he might do.

A day later, Supreme Leader Ayatollah Ali Khamenei branded Trump a “criminal”, acknowledging “several thousand deaths” that he blamed on “terrorists and rioters” linked to the US and Israel.

Iran’s judiciary indicated that executions may go ahead.

“A series of actions have been identified as Mohareb, which is among the most severe Islamic punishments,” Iranian judiciary spokesperson Asghar Jahangir told a press conference on Sunday.

Mohareb, an Islamic legal term meaning to wage war against God, is punishable by death under Iranian law.

The Iranian official told Reuters that the verified death toll was unlikely to “increase sharply”, adding “Israel and armed groups abroad” had supported and equipped those taking to the streets.

The clerical establishment regularly blames unrest on foreign enemies, including the US and Israel, an arch foe of the Islamic Republic, which launched military strikes in June.

Internet blackouts were partly lifted for a few hours on Saturday, but internet monitoring group NetBlocks said they later resumed.

One resident in Tehran said that last week, he had witnessed riot police directly shooting at a group of protesters, who were mostly young men and women.

Videos circulating on social media, some of which have been verified by Reuters, have shown security forces crushing demonstrations across the country.

The Iranian official, who declined to be named due to the sensitivity of the issue, also said some of the heaviest clashes and the highest number of deaths were in the Iranian Kurdish areas in the country’s northwest.

Kurdish separatists have been active there, and flare-ups have been among the most violent in past periods of unrest.

Three sources told Reuters on January 14 that armed Kurdish separatist groups sought to cross the border into Iran from Iraq in a sign of foreign entities potentially seeking to take advantage of instability.

Faizan Ali, a 40-year-old medical doctor from Lahore, said he had to cut short his trip to Iran to visit his Iranian wife in the central city of Isfahan as “there was no internet or communication with my family in Pakistan”.

“I saw a violent mob burning buildings, banks and cars. I also witnessed an individual stab a passer-by,” he told Reuters upon his arrival back in Lahore.