A Melbourne mother has launched an online campaign calling for gender equality in school uniforms.

Simone Cariss said it was unacceptable that there was not a pants option for girls at her daughter's Catholic school.

She launched an online petition on Friday night and has already collected more than 2,000 signatures.

Ms Cariss said her daughter Asha, who is in Year 1, loved the school but found the rule challenging.

"She feels at a disadvantage because she's wearing a heavy, cumbersome kilt with uncomfortable tights, and if she chooses not to wear tights, she has to wear socks and then she's cold. So it really is an impractical uniform," Ms Cariss told 774 ABC Melbourne.

"My daughter is really active; she likes to join in with the boys and the girls at lunchtime playing sports and running around.

"She doesn't choose to wear a dress at any other time, so she wants to have the choice."

Ms Cariss said she had been told by the school, who she has chosen not to name, that there was no plan to change the uniform policy.

"I feel there is anti-discrimination legislation out there, and a workplace wouldn't get away with this," she said.

"I don't know how schools are still able to do this and enforce this in 2016.

"What I don't understand is that it [pants] is an approved school uniform, it's just not available to half the students. And I don't think that's very fair."

Education Minister James Merlino said students should be able to wear pants if they want to.

"This is a Catholic school and a matter for Catholic Education but our policy with government schools is that they're advised to develop dress code requirements similar for both sexes," he said.

"My view is if a student wants to wear pants to school that student should be able to."