CCTV footage shows 16-year-old Armita Garawand's incident in a metro carriage in Tehran, reportedly leaving her in a coma.
Kurdish-focused rights group Hengaw claims the teen was attacked by female police officers for violating the strict dress rules for women.
Iranian authorities say she fainted due to low blood pressure, denying any involvement of security forces.
The incident occurs just over a year after the death in custody of Mahsa Amini, who had been arrested for allegedly violating the strict dress rules.
