Their demonstration in the capital Banjul on Monday (March 18) was taking place as lawmakers debated legislation that would do exactly that.
If Gambia's repeal bill is passed, then it would become the first country to reverse a ban on FGM.
It would also, says Amnesty International's West Africa researcher Michele Eken, be disastrous for women's rights - not only in Gambia but in the wider region.
"It would tell young girls, you know, your rights can be easily taken away. If this is passed, then what's next? We have to really be strong about it. And make sure that we don't take, take away something that took so long to fight for."
Gambia imposed steep fines and jail sentences in 2015 for those who carry out female circumcision.
The practice has no health benefits, the World Health Organization says, and can lead to excessive bleeding, shock, psychological problems and even death.
The number of women and girls worldwide who have undergone FGM has increased to 230 million from 200 million over the past eight years, the United Nations Children's Fund reported earlier this month.
UNICEF said the largest share were found in African countries, with over 144 million cases.
Eken said the most prominent voices in support of the practice come from men.
"...and we need to listen to women and young girls who've been through female genital mutilation and have the scars to show for it."
Gambia's repeal bill was presented earlier this month.
It argues that the ban violates citizens rights to practice their culture and religion, in what is an overwhelmingly Muslim country.
Members of parliament have come out both in favor of and against the bill.
On Monday, they voted by a margin of 42 to four to send the legislation to a parliamentary committee for review, parliament's speaker said.
The committee can make amendments to the bill and is expected to send it back to the national assembly for a vote - a routine procedure that usually takes at least three months.
