WASHINGTON -- US President Donald Trump on Thursday threatened again to strike Iran "very hard" if its authorities "start killing people" protesting in the Middle Eastern country.

"I have let them know that if they start killing people ... we are going to hit them very hard," Trump said in an interview with a conservative radio.

Trump and other senior US officials recently warned on several occasions that Washington would act if Iran "kills peaceful protesters."

On Wednesday, Iran's Foreign Ministry condemned what it described as "interventionist and deceptive" remarks by the Trump administration on recent unrest in the country, saying they reflected Washington's continued hostility toward the Iranian people.

The U.S. comments on Iran's internal affairs were part of a long-standing policy of pressure and interference, rather than genuine concern for the welfare of Iranians, said the ministry in a statement.