India, Jan. 9 -- US President Donald Trump on Thursday said that he will take severe action against Iran if its authorities "start killing people" who are protesting in Iran, where an economic crisis has led to a widespread unrest.

"I have let them know that if they start killing people, which they tend to do during their riots -- they have lots of riots -- if they do it, we are going to hit them very hard," Trump said during an interview with radio host Hugh Hewitt.

People in Iran's capital poured into the streets and shouted slogans from their homes on Thursday night after a call by the country's exiled crown prince for mass demonstrations, witnesses said, marking a new escalation in protests that have spread across the Islamic Republ...