Thousands of people, including many of Iranian origin, marched Saturday in to show support for nationwide protests in sparked by the death of last month.
They chanted slogans such as "Women, life, freedom" and "Justice for Iran" as they walked from the National Mall -- the vast green expanse that is home to the Washington Monument -- to the White House.
Siamak Aram, one of the organizers, said attendance would surpass 10,000 by the end of the procession and that this was the fifth such rally in Washington, in solidarity with women-led protests in Iran that are now in their sixth week.
"I believe this is the biggest one," Aram told AFP.
Some of the protesters came from other cities such as a 28-year-old woman from Boston who gave her name only as Mahshid and wore a T-shirt that read "Help free Iran."
"We do not want this tyrant regime anymore, who is banning us from our simple human rights and from our freedom," said Mahshid, who left Iran three years ago to complete a master's degree in architecture in the United States. Like other people at the rally, she declined to give her last name, fearing for kin that remain in Iran.
One sign held by a young woman had a hair strand attached to it and read: "Our hair may offend you but our mind will end you."
Amini died last month in police custody after her arrest for allegedly breaching Iran's strict dress code for women. Her death has fuelled the biggest protests seen in the Islamic republic for years.
Other rallies in support of the protesters in Iran were also held Saturday in Berlin and Tokyo.
In Washington, a woman named Marjan, aged 55, said she was pleased that the rally featured both people who have lived in Iran and others who have not.
"You see different ages, different religions, different beliefs," Marjan said.
A childhood friend of hers named Negar was visiting from Britain, where she said she has also attended rallies like this.
"This is an amazing revolution led by women really, and they're the most oppressed people in Iran," said Negar, 53.
Of Saturday's march in Washington, she said: "The least we can do is be here."