Iran has given no official death toll for the unrest, but Amnesty International said earlier this week that it had documented the deaths of at least 143 protesters, a total Tehran has said it rejects.
A figure anywhere close to that would make it the deadliest anti-government unrest at least since the authorities put down a "Green Revolution" of election protests in 2009, and probably since the 1979 Islamic Revolution itself.
Full details of the unrest have been difficult to report from outside Iran, especially as the authorities have shut down the internet.
The violence comes as Iran's economy has been hit by a tightening US blockade that cut off its oil exports this year, and as mass demonstrations have also erupted in Iraq and Lebanon against governments built around prominent pro-Iran factions.
"THUGS"
The disturbances began on Nov. 15 after the announcement of gasoline price hikes, but quickly turned political, with protesters demanding the removal of top leaders.
In response, the government has blamed "thugs" linked to exiles and the United States, Israel and Saudi Arabia.
"A deep, vast and very dangerous conspiracy that a lot of money had been spent on ... was destroyed by the people," Khamenei said in a meeting with members of the paramilitary Basij force which took part in the crackdown against protests, according to his official website.