US President Donald Trump is treading carefully around the issue of mass protests in Iran amid some US predictions that the unrest may not be widespread enough to challenge Tehran’s clerical establishment.

In recent days, Trump has warned Iranian leaders that there will be “hell to pay” if they crack down on the protest movement but he has otherwise adopted a wait-and-see attitude.

Human rights groups have alleged that security forces have killed and injured numerous protesters.

But in an interview with Fox News host Sean Hannity on Thursday, Trump only referred to demonstrators being “stomped on” in huge crowds and security forces “shooting the hell out of people” in the past.

The protests are the latest in a series of major demonstrations that have rocked Iran in which the US has spoken up on the side of the opposition.

Trump said he was not inclined now to meet Reza Pahlavi, the exiled 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.

“I think that we should let everybody go out there and see who emerges,” Trump told conservative radio host Hugh Hewitt on Thursday. “I’m not sure necessarily that it would be an appropriate thing to do.”

Pahlavi, who lives near Washington, has called on social media for continued mass demonstrations. In a post on Friday, he called on Trump to get more involved in the crisis with his “attention, support and action.”

“You have proven and I know you are a man of peace and a man of your word. Please be prepared to intervene to help the people of Iran,” he said.

US intelligence suggests Iran leadership still secure

Earlier this week, a US intelligence community assessment said that the protests were not big enough to challenge the leadership of Supreme Leader Ali Khamenei, according to a source familiar with US intelligence reports.

But US analysts were watching the situation carefully. The source said: “Prior to the last 24 hours the protests were broadly concentrated in cities where opposition to the regime has always been a thing. Moving to strongholds (like the Supreme Leader’s hometown of Mashad) is the significant development.”

“We don’t comment on matters of intelligence. As the President has stated repeatedly, if Iran shoots and violently kills peaceful protesters, ‘They will get hit very hard,’“ said a White House spokesperson.

The CIA declined to comment.

Iran’s unrest has come as Trump is preoccupied with his ouster of Venezuelan President Nicolas Maduro and has been floating the possibility of acquiring Greenland by purchase or military force.

Trump ordered US-led bombing raids on Iranian nuclear facilities last June and has warned he is prepared to do so again if Tehran tries to reconstitute the program.

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

Alex Vatanka, the director of the Iran program at the Middle East Institute think tank, said Trump appeared to be waiting to see if the protests could succeed in destabilising Iran’s ruling clerics before he decides to make good on his threats to intervene.

Trump “wants to be on the winning side, but he prefers a quick win, not a win that requires a lot of investment and holding hands, certainly not in the Middle East,” said Vatanka. “To him, that’s just against everything he stood for as a politician, going back to when he first ran.”