Donald Trump has threatened to intervene in Iran if its government killed demonstrators, prompting warnings from senior Iranian officials that any American interference would cross a “red line”.

In a social media post on Friday, Trump said that if Iran shoots and kills protesters, the US would “come to their rescue”. He added: “We are locked and loaded, and ready to go”, without explaining what that might mean in practice.

The protests, now in their sixth day, are the largest since 2022, when the death in police custody of 22-year-old Mahsa Amini triggered demonstrations across Iran. The current unrest was triggered by an unprecedented decline in the national currency on Sunday, with the Iranian rial dropping to about 1.4m to the US dollar, further exacerbating an already beleaguered economy.

Seven people have been killed, including a volunteer for the Basij security force, and videos have shown security forces carrying shotguns, with the sound of shooting in the background.

In response to Trump’s threat of intervention, Ali Shamkhani, adviser to the supreme leader, Ayatollah Ali Khameini, warned that Iran’s national security was a “red line, not material for adventurists tweets”.

“Any intervening hand nearing Iran security on pretexts will be cut off with a regret-inducing response,” Shamkhani said in a post on X.

The threats come just days after Trump said that the US could strike Iran if it was found to be rebuilding its nuclear programme, further escalating tensions between the two countries.

Another senior Iranian official, Ali Larijani, the secretary of Iran’s supreme national security council, accused the US and Israel of having a hand in the demonstrations in Iran, a common refrain by officials in response to protests.

“Trump must realize that US intervention in this domestic matter will lead to destabilisation of the whole region and the destruction of American interests,” Larijani wrote on X. “The American people must know that Trump is the one that started this adventure, and they should pay attention to the safety of their soldiers.”

Iran has threatened to target American soldiers stationed in the Middle East in the past, and in June it attacked Al-Udeid airbase in Qatar after the US struck Iranian nuclear enrichment sites.

The current protests have taken place in Tehran but have also spread to other cities, such as Isfahan in central Iran. Shopkeepers have closed their stores in protest and students have taken over campuses to express their grievances. Though economic conditions are the central grievance, demonstrators have also chanted anti-government slogans and decried what they said was corruption and mismanagement by the government.

The Iranian president, Masoud Pezeshkian, initially invited protest leaders for talks, taking a less confrontational approach than authorities did in the 2022 protests, which they violently suppressed. Pezeshkian said that he had instructed the government to listen to the protesters “legitimate demands”.

The recent deaths of demonstrators, however, could signal that authorities are taking a harder line against protests as they continue. A statement from the Iranian Revolutionary Guards Corps on Monday warned that it would take a harsh line against any foreign interference or “sedition” in the country.

As Iranian authorities grapple with protests at home, it has tried to stave off accusations from the US that it is reconstituting its nuclear programme. Iran has said that it is no longer enriching uranium anywhere in the country and has signaled it is open for negotiations with the west.