U.S. President Donald Trump issued a new warning to Iran’s leaders on Friday as videos showed anti-government protests raging across the country, and authorities blacked out the internet to curb growing unrest.

Rights groups have documented dozens of deaths of protesters in nearly two weeks and, with Iranian state TV showing clashes and fires, the semi-official Tasnim news agency reported that several police officers had been killed overnight.

Trump, who bombed Iran last summer and warned Tehran last week the U.S. could come to the protesters’ aid issued another warning on Friday, saying: “You better not start shooting because we’ll start shooting too.”

“I just hope the protesters in Iran are going to be safe, because that’s a very dangerous place right now,” he added.

However Trump said on Thursday he was not inclined to meet Reza Pahlavi, the U.S.-based crown prince and son of the late Shah of Iran, a sign that he was waiting to see how the crisis plays out before backing an opposition leader.