The protests erupted across the sanctions-hit country on November 15, after the price of petrol was raised by as much as 200 percent.
Authorities said some of the protest leaders in which police stations were attacked, petrol pumps torched and shops looted had been arrested.
"A full-fledged world war against the system and the revolution was born and fortunately the child died at the moment of birth," said Brigadier General Salar Abnoosh, a deputy head of the Basij, an Islamic volunteer militia.
Quoted by semi-official news agency ISNA late Thursday, Abnoosh said interrogations had revealed a "coalition of evil" made up of "Zionists, America and Saudi Arabia" was behind the "sedition".
The United Nations human rights office, for its part, has said it was alarmed by reports that live ammunition used by security forces to quell the unrest had caused a "significant number of deaths".
Officials have confirmed five deaths, while Amnesty International said that more than 100 demonstrators were believed to have been killed and the real death toll could be as high as 200.
Iran's Revolutionary Guards said that during the unrest, "incidents ... caused by the rise in petrol price took place in (a little) less than 100 cities".
The "incidents were ended in less than 24 hours and in some cities in 72 hours" as a result of the "armed forces' insight and timely action", it said.
- Internet partially restored? -
Internet remained mostly blocked in Iran on Friday for a sixth day, with officials and news agencies saying the blackout was gradually being rolled back.
Iran's telecommunications minister told ISNA that connectivity had returned in some provinces but did not give a date for full coverage.
"Other places will also be reconnected" upon orders of the Supreme National Security Council, said Mohammad-Javad Azari Jahromi, adding the ministry was still assessing damage done to businesses.
Access via ADSL was partially restored in a number of provinces and for some universities in Tehran as of Thursday, according to ISNA, although mobile data connections could still only access local websites.
NetBlocks, a website that monitors net shutdowns, showed Iran's connectivity to be at only 14 percent at mid-Friday.
The internet cut had helped "disrupt the complicated" plans by Iran's enemies, Abnoosh said.
The spokesman for Iran's Assembly of Experts called on authorities to keep "foreign networks" blocked after reconnection, saying they were "teaching people to riot, to commit crimes".
"If you are going to open it, I ask you to not fully open it," said Ayatollah Ahmad Khatami in a Friday prayer sermon broadcast live on state television.
The Assembly is an elected council of vetted clerics that oversees the work of Iran's supreme leader and has the authority to dismiss him.
- 'Leader of wickedness' -
Khatami has accused foreign powers of stoking the unrest and singled out the United States "as the leader of the wickedness".
The US "confessed to it, and unfortunately France and Germany went along too", he said.
Khatami said "the black regime of Saudi Arabia... also helped both with money and by providing media" coverage, and urged the Saudi people to "rise up" and no longer be "lackeys" of the US and Israel.
US President Donald Trump accused Iran of blocking the internet to cover up "death and tragedy".
"Iran has become so unstable that the regime has shut down their entire Internet System so that the Great Iranian people cannot talk about the tremendous violence taking place within the country," Trump tweeted.
US Secretary of State Mike Pompeo vowed to "expose and sanction the abuses" against protesters, urging Iranians to send "videos, photos and information documenting the regime's crackdown".
The European Union urged Iran to show "maximum restraint" in handling protests.
Tehran reacted by accusing the EU of interference and asking it "to explain why it doesn't keep its promises" to help bypass US sanctions that have plunged Iran's economy into recession.
Washington last year withdrew from the 2015 nuclear deal between Tehran and world powers and reimposed the sanctions on Iran, including vital sectors such as oil, banking and tech.