Sorcha Bierne (Sor-cha Bern), co-ordinator of the Fredericton Youth Feminists, says the government must repeal Regulation 84-20.
It requires abortions to be performed by specialists at approved hospitals and only after a woman gets approval from two doctors certifying that it is medically necessary.
Marie-Claude Blais, the minister responsible for women's equality, says she will take the concerns of the protesters to the government.
Liberal Opposition Leader Brian Gallant also spoke at the rally, saying he is pushing the government for a review of the province's abortion regulations.
But many of the protesters jeered the politicians, saying they want changes, not more study.
The protest follows the announcement last week that the Morgentaler Clinic in Fredericton will close at the end of July, saying it can't continue without government funding.