Thousands of supporters of the Iranian regime rallied in Tehran on Monday, accusing the US and Israel of instigating the most violent anti-government protests in at least a decade.
Amnesty International said on Monday at least 143 protesters were killed in anti-government demonstrations, which began on November 15 after the announcement of petrol price rises.
The protests have been the worst anti-government unrest in Iran since the authorities put down the "Green Revolution" of demonstrations against election fraud in 2009.
The government has blamed "thugs" linked to exiles and the US, Israel and Saudi Arabia for stirring up the street unrest.
Hossein Salami, the top commander of Iran's elite Revolutionary Guards, warned the US and its regional allies not to push Tehran into devastating retaliation over their support for "rioters".
"We have shown restraint but we will destroy our enemies, America, Israel and Saudi Arabia if they cross our red lines," Mr Salami told pro-government demonstrators in Tehran's Revolution Square, state TV reported.
Iranian TV carried live footage of crowds chanting "Death to America," and "Death to Israel".
It and Iranian officials had promoted the state-sponsored rally since Sunday in response to western statements of solidarity with the fuel price protesters.
"I recommend they look at the marches today to see who the real people in Iran are and what they are saying," Foreign Ministry spokesman Abbas Mousavi said.
The unrest has come as US sanctions imposed this year have cut off nearly all of Iran's oil exports, and as similar protest movements have erupted in Iraq and Lebanon against governments that include heavily armed pro-Iranian factions.
Amnesty said Iran's "use of lethal force against protesters" must be globally condemned and that verified videos showed "security forces deliberately shooting unarmed protesters from a short distance".
"In some cases, protesters were shot while they were running away and clearly posed no threat to the security forces," Amnesty said.
"Other videos show security forces shooting towards protesters from rooftops of state buildings, including a Justice Department building."
Iran's fuel protests have quickly turned to rallies calling on top leaders to quit.
"Death to the dictator. Time for you to step down," protesters have chanted in social media videos posted by Iranians.
Details have been difficult to report in part because of an internet cut in much of the country.
State authorities warned protesters of severe punishment if unrest continued.
They said late last week that disturbances had ceased, although unverified videos posted on social media showed sporadic protests were continuing in some places.
Washington has sided with Iran's protesters, and European states including France and Germany have expressed deep concern over reports of many deaths during the protests.
Social media footage has shown police on motorbikes driving into crowds and attacking protesters with clubs. Other videos showed police firing at people with live ammunition.
Iran has rejected Amnesty's death toll figures. It says several people, including members of the security forces, have been killed and more than 1,000 people arrested.
The Centre for Human Rights in Iran, an advocacy group in New York, said the number of arrests was probably closer to 4,000.
"My cousin has been arrested. We don't know where he is and whether he is alive or not," a young protester in Tehran said by phone.