TEHRAN, Jan 18 (Reuters): Iran's president warned on Sunday that any U.S. 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.

U.S. 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 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".

Photo from Reuters