Iranian officials accused the country's "enemies" of instigating and orchestrating the protests - the country's first large-scale demonstrations since the 2009 election.
Mahmoud Sadeghi, a Tehran MP, announced the official count on Tuesday after the state-run ICANA news agency reported that 1,000 people had been arrested during the week of demonstrations that began in December.
The violence that broke out at several protests killed 22 people after unrest spilled into more than 80 cities across Iran.
The number is far higher than the one initially offered by authorities.
Officials have said the majority have since been released, with only the main "instigators" facing trial.
Iranian authorities have said that the protests are waning.
Authorities also have deployed additional police and members of the Basij, a volunteer organisation affiliated with Iran's paramilitary Revolutionary Guard.
It remains hard for journalists and outsiders to piece together what's happening beyond Tehran, as Iran is a vast country of 80 million and travel there is restricted.
UK Foreign Minister Boris Johnson told the British Parliament Tuesday that "it is vital that the people of Iran and government of Iran should understand that we in this country support right to peaceful demo within the law".
"Iran's regime claims to support democracy, but when its own people express their aspirations for better lives and an end to injustice, it once again shows its true brutal nature", White House Press Secretary Sarah Sanders said.
USA officials and analysts studying Iran believe conservative opponents of President Hassan Rouhani, a relative moderate within Iran's clerically overseen government, started the demonstrations in Mashhad, but quickly lost control of them.
The new figures come as Iran's Supreme Leader Ayatollah Ali Khamenei said Tuesday that the country had struggled for 40 years against attacks on "the revolution" and would not be daunted now.
Khamenei, however, also stressed that those with legitimate complaints about Iran's economy should be heard. "These should be distinguished from each other".