The 24-year-old Pegah Agangarani was twice detained in the past, though she was released without charges once during opposition protests over the 2009 re-election of former President Mahmoud Ahmadinejad, and the second time in 2011.
She has since been banned from traveling abroad.
She has backed Iran's new, moderate President Hassan Rouhani, who has professed more tolerant views on social and cultural issues.
Today's report by the pro-reform Shargh daily quotes Agangarani's mother, Manijeh Hekmat, as saying the actress has been sentenced to 18 months.