The head of Iran's judiciary told the country's attorney general and prosecutors Monday to show "no leniency" for rioters.

"I instruct the attorney general and prosecutors across the country to act in accordance with the law and with resolve against the rioters and those who support them... and to show no leniency or indulgence," Gholamhossein Mohseni Ejei said, according to the judiciary's Mizan news agency, France 24 reported.

He added that Iran "listens to the protesters and their criticism, and distinguishes between them and rioters."

The remarks came after President Trump warned that Iran would "get hit very hard by the United States" if the authorities killed more demonstrators.

Last week, protests erupted when shopkeepers in the capital of Tehran went on strike over high prices and economic stagnation. Demonstrations have since spread to other cities and expanded to include political demands.

There have been protests in 23 of Iran's 31 provinces, which have affected at least 45 different cities, most of them small or medium-sized and concentrated in the west, according to an AFP tally based on official statements and media reports.

Since Tuesday, at least 12 people have been killed in localized clashes, including members of the security forces, according to official announcements.

Mizan reported that police intelligence officers in Tehran have identified a suspected rioter hideout and seized "weapons, ammunition, and materials for making improvised explosive devices."

Iran's economy has been hit hard by international sanctions, with the national currency losing more than a third of its value against the U.S. dollar over the past year and inflation reaching double digits.

On Sunday, the government announced a monthly allowance for every citizen to help alleviate economic pressure, equivalent to around 3.5% of the average monthly wage.

Most shops in Tehran were open on Monday, according to AFP reporters in the capital. Riot police were deployed at major intersections, though, and officers were stationed in front of some schools. Several universities in the city have resumed classes, but only online.