The protests turned violent in a number of locations and state media report that at least 21 people have been killed in clashes with security forces.
It hikes the death toll to at least 20 people following six days of demonstrations.
What began on December 28 in the city of Mashhad as a protest against a weak economy and surging food prices has spread across Iran, with demonstrators criticizing Iran's government and supreme leader Ayatollah Ali Khamenei.
Protesters in Iran took to the streets across dozens of cities for a sixth night Tuesday in what has become the biggest challenge to the Islamic regime in years. Silent at first on the unrest, the state-owned Islamic Republic of Iran Broadcasting has followed the reformists' explanation for the burgeoning trouble, citing economic problems as the root cause of the confrontations that are turning increasingly deadly. It said all three were shot with hunting rifles, which are common in the Iranian countryside.
The latest demonstrations, which largely seemed to come out of nowhere and have surprised the authorities with their size and intensity, appear to be rooted in anger toward President Hassan Rouhani, who is regarded as a moderate, and his inability to bring change to an economy that has long suffered under the weight of sanctions.
Many Iranians resent the country's costly foreign interventions in places such as Syria and Iraq, and want their leaders to create jobs at home, where youth unemployment reached 29 percent a year ago. "Even those who are confronting the rioters should act within the framework of law", he said.
"I demand all prosecutors across the country to get involved and the approach should be strong", he said.
Iran's Revolutionary Guards said Wednesday that the unrest that rocked Iran over several days was at an end, and claimed that a maximum of 15,000 people had taken part nationwide.
In an apparent attempt to stave off more unrest, the authorities began blocking access to photo-sharing and online messaging services on mobile phones, including Telegram, which the government accused of being used to foment violence, local media and Telegram's CEO said.
The secretary of Iran's Supreme National Security Council, Ali Shamkhani, blamed the United Kingdom, the USA and Saudi Arabia for fomenting the protests on social media. Rouhani was quoted as saying in a meeting with lawmakers.
Mahmodi said he hopes Iranians overthrow the current religious regime and put in place a secular government.
Ali Shamkhani, the secretary of Iran's Supreme National Security Council, also weighed in on Iran's protests.
That improvement has not reached the average Iranian, however. However, the circumstances of the most recent deaths remain unclear and unconfirmed.