Yet a second woman, identified by human rights groups as Narges Hosseini, was arrested on Monday for participating in the protest.
In Iran, women showing their hair in public can be jailed up to two months or fined United States dollars 25.
She was dubbed "the girl from Enghelab Street" as word - and memes - of her action spread.
They show at least nine other women posing in similar fashion in Tehran and the central Iranian city of Isfahan.
During December's protests, a woman called Vida Movahedi took off her hijab and stood on Enghelab street, which translates as "Revolutionary Street", in Tehran's university district waving a white scarf.
LONDON, The Iranian authorities have released most of the people arrested during December's anti-government protests but around 300 remain in jail facing charges, Iran's interior minister said on Tuesday.
Writing on her Facebook page, Sotoudeh said that women should be given the right "to manage" their own bodies.
"That directive was an important step forward, but more or less reflected the reality on the ground in the capital where hijab has been increasingly loosely adhered to in some quarters", Gissou Nia, a human rights lawyer based in Las Angeles and focused on Iran, told Newsweek. But in 1941 Reza Shah abdicated to the Crown Prince Mohammad-Reza, who relaxed the dress code and allowed women to wear the hijab if they chose. One video posted on social media on Wednesday showed a mother at a busy traffic intersection in Tehran waving a white scarf and shouting out: "We want freedom, we want freedom of dress". Both Rouhani and Supreme Leader Ayatollah Ali Khamenei support softer attitude toward women with improper hijab, though hard-liners opposed to easing such rules still dominate Iran's security forces and judiciary.
"The first demonstrations against the hijab took place a few days after the revolution on March 8, 1979".
Women who violate the country's dress code will be sent to classes on Islamic values instead of being arrested.
The woman from the iconic protest image that activists have been imitating was reportedly freed on Monday after spending about a month in jail.
Many on social media applauded and encouraged these women for standing up against rigid laws.