Thousands gathered near the grave of the Kurdish woman and clashed with security, 40 days since her death. A rights group and witnesses said officers fired live rounds and tear gas at the crowds in the city.
Protests swept across Iran after Ms Amini, 22, died on 16 September.
On Wednesday, security forces were deployed in Saqqez and other parts of Kurdistan province, in anticipation of fresh demonstrations on the 40th day of mourning for Ms Amini - a culturally significant occasion for Iranians. One young female protester inside Iran told BBC World News: “You cannot imagine how tough it is to go to streets knowing that they are ready to shoot. But we are not afraid. “It's not about me. It's about the next generation. We want to have a normal life.”
She added: “I don't know when our protests will come to an end, but today Iranian society is more awake than ever and we are ready for big changes.”
