Iran's president says protesters should be "dealt with decisively" following nationwide anti-government unrest sparked by the death of a young woman in police custody.
Iranian state TV suggests 26 protesters and police have been killed since violence erupted last weekend. Other reports put the figure as high as 35.
President Ebrahim Raisi said Iran must "deal decisively with those who oppose the country's security and tranquility", state media reported.
State-organised rallies took place in several Iranian cities on Friday to counter the anti-government demonstrations, and the army has promised to confront "the enemies" behind the unrest.
Mr Raisi's comments were made in a condolence phone call to the family of a security agent stabbed to death in the northeastern city of Mashhad, allegedly by protesters against the regime.
The president "stressed the necessity to distinguish between protest and disturbing public order and security, and called the events... a riot", according to state media.
The morality police detained Ms Amini last week, saying she did not properly cover her hair with a headscarf - known as the hijab - which is mandatory for Iranian women.
Ms Amini, who was Kurdish, collapsed at a police station in the capital Tehran, fell into a coma, and died three days later in hospital on Friday 16 September.
Authorities said she allegedly had a heart attack but her family reportedly said she had no history of heart disease.
And according to her father, Ms Amini suffered bruising to her legs while in custody. He has said he holds the police responsible for her death.
During the street protests, women have played a prominent role, challenging the country's Islamic dress code, and waving and burning their veils.
Some have publicly cut their hair as furious crowds called for the fall of Supreme Leader Ayatollah Ali Khamenei.
The protests have spread to most of the country's 31 provinces, including Tehran.
Iran's police chief Hossein Ashtari has issued a tough message in an attempt to stop the demonstrations.
"The people's security is our red line," he told state TV.
"Those involved in sabotage and creating insecurity based on directives from outside the country should know that they will be strongly dealt with."
The morality police are attached to Iran's law enforcement, and their role is to ensure the respect of Islamic morals as described by the country's clerical authorities.
The anti-government protests are not expected to pose an immediate threat to the rulers, whose security forces have crushed similar demonstrations in recent years, analysts say.
But the protests have clearly made authorities nervous.