Iran's police command said on Wednesday that the force would come down hard on protesters who took to the streets after the death of a young Iranian-Kurdish woman in custody.
Mahsa Amini, 22, died on September 16 while being held by the so-called morality police for allegedly wearing a headscarf incorrectly.
The police command said that “officers will oppose with all their might the conspiracies of counter-revolutionaries and hostile elements, and deal firmly with those who disrupt public order and security anywhere in the country,” according to Fars news agency.
At least 76 people have been killed in the protests, a rights group said.
UN Secretary General Antonio Guterres “stressed to President Raisi the need to respect human rights, including freedom of expression, peaceful assembly and association” in a meeting between the two at the UN General Assembly last week, spokesman Stephane Dujarric said.
“We are increasingly concerned about reports of rising fatalities, including women and children, related to the protests,” Mr Dujarric added.
He said Mr Guterres “calls on the security forces to refrain from using unnecessary or disproportionate force and appeals to all to exercise utmost restraint to avoid further escalation”.
He also called for a “prompt, impartial and effective investigation” into the death of Amini, who died in custody after allegedly breaching rules that mandate tight-fitting hijabs, leading to nationwide protests in which dozens have been killed.
Mr Raisi on Saturday called the protests riots and urged “decisive action against the opponents of the security and peace of the country and the people”, his office said.
Riot police in body armour were beating protesters with truncheons in running street battles, reports said on Tuesday.
Students tore down large pictures of supreme leader Ayatollah Ali Khamenei and his late predecessor Ayatollah Ruhollah Khomeini, according to recent video footage published by AFP.
Dozens of young Iranians and Americans on Tuesday gathered in front of The New York Times building in Manhattan to demonstrate for the rights of women in Iran.
Activist Forouzan Farahani knelt on the pavement in front of the building and shaved her head in an act of protest at Amini's death.
“We are here today to protest [against] the murder of Mahsa in Iran and uprisings that are ongoing across Iran in different cities,” said Ms Farahani, 31.
The Iranian told AFP the demonstrators were also protesting against “bias and selective narrative” in The New York Times coverage of Iran in recent years.
“We also think that they don't have a neutral position and so we think that it's good to come to here and protest,” Ms Farahani said.
The protesters singled out Farnaz Fassihi, a New York-based reporter for the newspaper, who is covering the crisis in Iran.
“We stand by our reporting of the unrest in Iran, which is led by Farnaz Fassihi, an experienced journalist who has covered the Middle East for the past 25 years,” a representative of the paper told AFP.