Amini, 22, from the Iranian Kurdish city of Saqez, was arrested this month in Tehran for "unsuitable attire" by the morality police that enforces the Islamic Republic's strict dress code.
Her death has sparked the first big show of opposition on Iran's streets since authorities crushed protests against a rise in fuel prices in 2019.
Despite a growing death toll and a fierce crackdown by authorities, videos posted on Twitter showed demonstrators calling for the fall of the clerical establishment while clashing with security forces in Tehran, Tabriz, Karaj, Yazd and many other Iranian cities.
State television said police clashed with what it called "rioters" in some cities and fired tear gas to disperse them.
Videos posted on social media from inside Iran showed protesters chanting, "Woman, Life, Liberty", while women waved and burnt their veils.
Videos on Twitter showed protesters chanting "Death to the dictator" in the city of Tabriz, a reference to Iran's top authority Supreme Leader Ayatollah Ali Khamenei. In the Kurdish cities of Sanandaj and Sardasht, riot police fired at protesters, videos on Twitter showed.
"I will kill those who killed my sister," chants of protesters could be heard in one of the videos from Tehran.
Social media posts, along with some activists, have called for a nationwide strike. Several university teachers have resigned in protest against Amini's death, according to statements published by them on social media.
Students in several universities have refused to participate in classes in protest against the widespread arrest of students and forceful encounters with security forces in universities.
The videos on social media and resignation reports could not be verified by Reuters.
Amini's death has drawn widespread international condemnation while Iran has blamed "thugs" linked to "foreign enemies" for stirring up unrest.
Tehran has accused the United States and some European countries of using the unrest to try to destabilise the Islamic Republic.
The officials said 41 people, including members of the police and a pro-government militia, died during the protests. But Iranian human rights groups have reported a higher toll.
The Iranian human rights group Hengaw said "18 were killed, 898 people were injured and over 1000 Kurdish protesters have been arrested in the last ten days", estimating the figures to be higher.
Iran's judiciary has set up special courts to try "rioters", according to state media.
To make it difficult for protesters to post videos on social media, authorities have restricted internet access in several provinces, according to Internet blockage observatory NetBlocks on Twitter and sources in Iran.Â
