US President Donald Trump and a top Iranian security official traded threats Friday as protests spread across parts of Iran.

Trump warned on Truth Social that "if Iran shots [sic] and violently kills peaceful protesters," the US would intervene, adding, "We are locked and loaded."

He made the remarks as human rights groups said several people had been killed by security forces in Iran's biggest protests since 2022, when the death of 22-year-old Jina Mahsa Amini in police custody triggered nationwide demonstrations.

Ali Larijani, a former parliament speaker and current secretary of Iran's Supreme National Security Council, accused the US and Israel of fueling the demonstrations. He warned that Washington's intervention would lead to chaos across the region.

"The people of the US should know that Trump began the adventurism. They should take care of their own soldiers," he wrote on X.

Protests sparked by failing economy

Protests in Iran erupted after a sharp currency collapse last Sunday, with $1 now costing about 1.4 million rials.

Initially led by traders in Tehran, the demonstrations have widened into demands for broad change and have spread nationwide.

Mahmood Amiry-Moghaddam, director of the Norway-based NGO Iran Human Rights, told DW people are "calling for a regime change."

"I don't think that authorities have any other option, either they should give up or they should use, the violence, and based on what we have seen in previous protests, unfortunately, they are going to use heavier violence against protesters."

On Thursday, severe riots in the west left several dead in clashes with security forces.

"The people of Iran properly know the experience of 'being rescued' by Americans: from Iraq and Afghanistan to Gaza," Ali Shamkhani, an adviser to Supreme Leader Ayatollah Ali Khamenei said.

He added "any interventionist hand that gets too close to the security of Iran will be cut."

Reform in Iran must come from within, analyst says

Iran's economy has struggled for years since the US reimposed sanctions in 2018, after Trump withdrew from an international nuclear agreement during his first term.

In June 2025, the US military joined Israel's war against Iran and bombed Iranian nuclear sites. Iran responded with a strike on a US military base in Qatar.

Trump's social media posts offered little clarity on his specific plans..

Scott Lucas, a professor of American studies at University College Dublin, told DW, "Change, if it is going to come, cannot be imposed on Iran from the outside."

"You have to be very, very careful not to be seen endorsing violence against the regime because you will give them the pretext to strike back and strike back hard," he said.

"Probably the best approach ... is that you encouraged that call for peaceful reform, for women's rights, for economic rights, for social rights, that you go ahead and pay attention to the peaceful protest," Lucas added.

Edited by: Sean Sinico