"Today, on the 15th September 2024, 34 female political prisoners in Evin Prison have gone on a hunger strike in commemoration of the second anniversary of the 'Woman, Life, Freedom' movement and the killing of Mahsa (Jina) Amini," it said.
Amini was a 22-year-old Iranian Kurd whose death in custody after her arrest for allegedly violating the strict dress code for women sparked the demonstrations.
The prisoners had abstained from food "in solidarity with the protesting people of Iran, against the government's oppressive policies," the foundation added.
Mohammadi, who has campaigned against the compulsory wearing of the hijab and the death penalty in Iran, has been in Tehran's Evin prison since November 2021.
She has spent much of the past decade in and out of jail and has staged repeated hunger strikes.
"On the second anniversary of the 'Women, Life, Freedom' movement, we reaffirm our commitment to achieving democracy, freedom, and equality and to defeating theocratic despotism," Mohammadi said in a statement on her official X account.
"Today, we raise our voices louder and strengthen our resolve."
Mohammadi's children received the Nobel Peace Price on her behalf in 2023 while she was incarcerated.
According to her family, she was on hunger strike at the time in solidarity with the Baha'i community, Iran's largest religious minority who say they are targeted by discrimination.
UN experts last month accused Iran of denying Mohammadi proper healthcare.
She "was reportedly subjected to physical violence" in Evin on August 6, during which she "allegedly lost consciousness, and sustained injuries to her ribcage and other parts of her body", the experts said.
Iranian authorities acknowledged a confrontation had taken place, but blamed Mohammadi for "provocation" and denied any prisoners had been beaten.
Women-led protests erupted after Amini died in custody on September 16, 2022.
The protests rattled Iran's leadership that autumn and winter, but authorities crushed them, with rights group Amnesty International saying security forces used assault rifles and shotguns in the crackdown.
Human rights groups say at least 551 people were killed. Thousands more were arrested, according to the United Nations.
