Taraneh Alidoosti posted an image on Instagram that showed her holding a sign with the slogan that has become the rallying cry of the nationwide protest movement: "Woman. Life. Freedom."
People in western Iran went on strike in solidarity with mourners marking 40 days since troops killed dozens in a crackdown on protests.
Security forces opened fire on demonstrators on September 30 after weekly prayers in Zahedan, capital of Sistan and Baluchestan province on the border with Pakistan.
It came two weeks after demonstrations broke out across Iran over the death of Mahsa Amini, a 22-year-old Kurdish woman, following her arrest in Tehran for breaching the country's strict dress code for women.
The violent crackdown on nationwide protests over her death has killed at least 304 people, including 41 children and 24 women, Oslo-based group Iran Human Rights has said.
Activists distributed pamphlets calling for protests in all cities on Wednesday for the 40-day mourning ceremony of Zahedan's "Bloody Friday", a video shared by the 1500tasvir social media channel showed.
Widespread strikes were held in solidarity with Zahedan and the Kurdish cities of Baneh, Bukan, Kermanshah, Marivan, Sanandaj and Amini's home town of Saqqez, in the country's west, the Hengaw rights group said.
The cause of the violence that IHR said left at least 92 dead in Zahedan on September 30 was the alleged rape in custody of a 15-year-old girl by a police commander in the province's port city of Chabahar.
But analysts say the demonstrators were inspired by the protests that flared after Amini's death.
The rallies were initially driven by women's rights but have expanded over time to include other grievances.
"The 2022 protests are a convergence of angry and frustrated Iranians with the same goal, overthrowing the Islamic republic and a theocratic regime," said Saeid Golkar, from the University of Tennessee at Chattanooga in the US.
The poverty-stricken Sistan and Baluchestan province is a flashpoint for clashes with drug smugglers, as well as rebels from the Baluch minority and other extremist groups.
Activists have long complained that the region has been the target of discrimination by Iran's Shiite clerical leadership, with disproportionate numbers of Baluchs killed in clashes every year, as well as executions.
Protests over Amini's death have shown no signs of abating despite the brutal crackdown and a campaign of mass arrests.
Young women have led the way, removing and burning their head coverings, chanting anti-regime slogans and confronting the security forces on the streets.
On Wednesday, reformist parties called for "courageous and innovative changes" including a referendum in a bid to end the crisis, according to the Iranian Reform Front, founded last year by officials close to former president Mohammad Khatami.
But Henry Rome, an Iran expert at the Washington Institute think tank, suggested the "call will almost certainly wither".
"The regime is unable to coalesce around even modest reforms to defuse the protests. In a moment of turbulence, there's little prospect it would go so far as to put itself on the ballot," he said.
Iran has struggled to suppress the demonstrations, which have evolved into its biggest challenge since a revolution in the country in 1979.
Troops have used live ammunition, bird shot, tear gas and paintballs on protesters.
'We won't let up'
Iran has sought to portray the protest movement as a plot hatched by its enemies in the West, with Britain, Canada, the EU and the US imposing sanctions over human rights violations.
The EU will seek to adopt further restrictions next week, German Foreign Minister Annalena Baerbock said on Wednesday.
"We won't let up. We stand with the men and women of Iran, not only today, but as long as it is necessary," she said.