The death toll in the protests that have been raging in Iran since Thursday has reached 12, state television announced on Monday.
Ten of the victims alone were killed during protests on Sunday.
"In the events of last night, unfortunately, a total of about 10 people were killed in several cities," state television said while showing footage of damage from the demonstrations. It gave no further details of the deaths.
The nationwide protests have drawn in tens of thousands of people and represent the boldest challenge to Iran's leadership since pro-reform unrest in 2009. Calls for more demonstrations on Monday raise the possibility of prolonged instability.
Unsigned statements posted on social media urged Iranians to demonstrate again in the capital Tehran and 50 other urban centers.
The Iranian Interior Ministry said that it had not received requests for demonstrations to be held on Monday.
Iran is a major OPEC oil producer but frustrations have grown at home while the country is deeply involved in Syria and Iraq.
Those foreign interventions are also fueling anger in the Islamic Republic because Iranians want their leaders to create jobs instead of engaging in costly proxy wars.
The unrest erupted in the second city of Mashhad against price rises but it swiftly spread and turned into political rallies.
Some called on Supreme Leader Ali Khamenei to step down and chanted against a government they described as thieves.
Demonstrators say they are angry over corruption and economic hardship in a country where youth unemployment reached 28.8 percent last year.
Protests continued overnight even though President Hassan Rouhani appealed for calm. In remarks carried on state TV, he said Iranians had the right to criticize authorities but also warned of a crackdown.
"The government will show no tolerance for those who damage public properties, violate public order and create unrest in the society," Rouhani said. Hundreds of people have been arrested but security forces have largely shown restraint.
Footage circulated on social media showed security forces opening tear gas at the protesters. Over the weekend, other footage showed the two sides pelting each other with rocks.
Two people were shot dead in the southwestern town of Izeh on Sunday and several others were injured, ILNA news agency quoted a member of parliament as saying. It was not clear if the two dead were part of the 10 cited on state television.
Authorities blamed the deaths on foreign agents.
"I do not know whether yesterday's shooting was done by rally participants or the police and this issue is being investigated," Hedayatollah Khademi was quoted as saying.
Regional governor Mostafa Samali told the semi-official news agency Fars that just one person had been killed and that the incident was unrelated to the protests and the alleged shooter had been arrested.
Police in the center of Tehran fired water cannon on Sunday to try to disperse demonstrators, according to pictures on social media.
Demonstrations turned violent in Shahin Shahr in central Iran. Videos showed protesters attacking the police, turning over a car and setting it on fire.
There were also reports of demonstrations in the western cities of Sanandaj and Kermanshah as well as Chabahar in the southeast and Ilam and Izeh in the southwest.
Videos showed people in central Tehran chanting: "Down with the dictator!" in an apparent reference to Khamenei.
Protesters in Khorramabad in western Iran shouted: "Khamenei, shame on you, leave the country alone!"
The government said it would temporarily restrict access to the Telegram messaging app and Instagram, owned by Facebook Inc, state television said. There were also reports that mobile access to the internet was being blocked in some areas.
"Iran, the Number One State of Sponsored Terror with numerous violations of Human Rights occurring on an hourly basis, has now closed down the Internet so that peaceful demonstrators cannot communicate. Not good!" US President Donald Trump tweeted on Sunday.