Iran’s supreme leader signaled Friday that Tehran would crack down hard on protesters who have demonstrated against the theocratic regime for nearly two weeks after dramatic images showed riots breaking out across the country Thursday night.

Ayatollah Ali Khamenei, 86, condemned what he called “a bunch of rioters [who] destroyed a public building just to please the president of the United States.”

“Iranians must maintain their unity,” added Khamenei in remarks aired on state television to an audience chanting “Death to America!”

“Let everyone know that the Islamic Republic came to power [in 1979] with the blood of hundreds of thousands of honorable people,” the supreme leader added. “Iran will not tolerate mercenaries working in the interests of foreigners.”

Iran’s judiciary chief Gholamhossein Mohseni-Ejei separately vowed that punishment for protesters “will be decisive, maximum and without any legal leniency.”

Thursday’s demonstrations came in response to a call for action by Iran’s exiled crown prince, Reza Pahlavi, and despite Tehran cutting off the internet and international telephone calls.

Videos shared by activists online showed protesters chanting anti-Khamenei and pro-monarchy slogans as symbols of the regime — including buildings and monuments linked to the notorious Islamic Revolutionary Guard Corps — were torched.

Iranian state media broke its silence over the unrest Friday, alleging “terrorist agents” of the US and Israel set fires and sparked violence. Official sources also reported “casualties,” without elaborating.

Khamenei claimed the demonstrators were responding to Trump’s Jan. 2 announcement that the US would “come to their rescue” if the hardline Shia regime launched violent repression.

“We are locked and loaded and ready to go,” Trump had added, without elaborating.

“He said that he would come to their aid,” the ayatollah said of the American president. “He should pay attention to the state of his own country instead.”

Thursday marked yet another escalation in protests that began Dec. 28 over Iran’s ailing economy and have mushroomed into the most significant challenge to the government in at least three years.

According to the US-based Human Rights Activists News Agency, which relies on a network of activists inside Iran for its reporting, violence around the demonstrations has killed at least 42 people while more than 2,270 others have been detained.

The crown prince, 65, the son of the late shah who was deposed by the 1979 revolution, has called for demonstrations at 8 p.m. local time Friday (11:30 a.m. ET)

“What turned the tide of the protests was former Crown Prince Reza Pahlavi’s calls for Iranians to take to the streets at 8 p.m. on Thursday and Friday,” Holly Dagres, a senior fellow at the Washington Institute for Near East Policy, told the Associated Press. “Per social media posts, it became clear that Iranians had delivered and were taking the call seriously to protest in order to oust the Islamic Republic.”

“This is exactly why the internet was shut down: to prevent the world from seeing the protests. Unfortunately, it also likely provided cover for security forces to kill protesters.”

When the clock struck 8 p.m. Thursday, neighborhoods across Tehran erupted in chanting, witnesses said. The chants included “Death to the dictator!” and “Death to the Islamic Republic!” Others praised the shah, shouting: “This is the last battle! Pahlavi will return!”

“Iranians demanded their freedom tonight. In response, the regime in Iran has cut all lines of communication,” the crown prince said. “It has shut down the Internet. It has cut landlines. It may even attempt to jam satellite signals.”

He went on to call for European leaders to join Trump in promising to “hold the regime to account.”

“I call on them to use all technical, financial, and diplomatic resources available to restore communication to the Iranian people so that their voice and their will can be heard and seen,” he added. “Do not let the voices of my courageous compatriots be silenced.”

Pahlavi had said he would offer further plans depending on the response to his call. His support of and from Israel has drawn criticism in the past — particularly after the 12-day war between Iran and the Jewish state this past June.

The internet cut also appears to have taken Iran’s state-run and semiofficial news agencies offline as well. The state TV acknowledgment at 8 a.m. Friday represented the first official word about the demonstrations.

State TV claimed the protests saw violence that caused casualties but did not elaborate. It also said the protests saw “people’s private cars, motorcycles, public places such as the metro, fire trucks and buses set on fire.”

As sanctions tightened and Iran struggled after the 12-day war, its rial currency collapsed in December, reaching 1.4 million to $1. Protests began soon after, with demonstrators chanting against Iran’s theocracy.

In an interview with talk show host Hugh Hewitt aired Thursday, Trump reiterated his Jan. 2 pledge.

Iran has “been told very strongly, even more strongly than I’m speaking to you right now, that if they do that, they’re going to have to pay hell,” Trump said.

The president demurred when asked if he’d meet with Pahlavi.

“I’m not sure that it would be appropriate at this point to do that as president,” Trump said. “I think that we should let everybody go out there, and we see who emerges.”

With Post wires