At least 41 people have died since the unrest began, mostly protesters but also members of the Iranian security forces, according to an official toll.
Iranians defied a warning from the judiciary and took to the streets for a 10th consecutive night on Sunday to protest the death of young woman Mahsa Amini in morality police custody.
Echoing an earlier warning by President Ebrahim Raisi, judiciary chief Gholamhossein Mohseni Ejei on Sunday "emphasised the need for decisive action without leniency" against the core instigators of the "riots", the judiciary's Mizan Online website said.
At least 41 people have died since the unrest began, mostly protesters but including members of the Iranian security forces, according to an official toll. Other sources say the real figure is higher.
Oslo-based Iran Human Rights (IHR) on Sunday evening said the death toll was at least 57, but noted that ongoing internet blackouts made it increasingly difficult to confirm fatalities in a context where the women-led protests have spread to scores of cities.
Hundreds of demonstrators, reformist activists and journalists have been arrested during the mostly night-time demonstrations since unrest first broke out after Amini's death was announced on September 16.
Amini was detained three days before that for allegedly breaching rules mandating tightly fitted hijab head coverings and which ban, among other things, ripped jeans and brightly coloured clothes.
Witnesses told AFP news agency that protests were continuing in several locations. Video footage showed demonstrations in Tabriz and Shiraz, among other places, with women removing their headscarves and protesters shouting against the authorities.
Iran's President Ebrahim Raisi vows "decisive action" against wave of unrest that has rocked country since death of Mahsa Amini in custody of morality police. Reza Hatami has more pic.twitter.com/vYiF1jchyB— TRT World Now (@TRTWorldNow) September 25, 2022
Among the protesters were women who burnt their hijabs and cut off their hair. Some danced near large bonfires to the applause of crowds that have chanted "zan, zendegi, azadi" or "woman, life, freedom".
Video of demonstrations on Saturday, verified by AFP, showed students ripping down a picture of supreme leader Ayatollah Ali Khamenei outside a university in the northern province of Mazandaran.
Web monitor NetBlocks noted "rolling blackouts" and "widespread internet platform restrictions" on Sunday, with WhatsApp, Instagram and Skype already blocked.
This followed older bans on Facebook, Twitter, TikTok and Telegram.
Protests abroad in solidarity with Iranian women have been held in Athens, Berlin, Brussels, Istanbul, Madrid, New York and other cities.
In Paris and London on Sunday, police clashed with demonstrators trying to reach Iran's embassies. French officers fired tear gas. In London, 12 people were arrested and five officers seriously hurt, police there said.
Iran has also organised large rallies in defence of the hijab and conservative values.
At the main pro-government event held on Sunday in central Tehran's Enghelab (Revolution) Square, demonstrators voiced support for mandatory hijab laws.