The protest by the Canberra Mums groups follows an online petition, which attracted more than 13,000 signatures since launching last month in the wake of the sentencing of a paedophile who sexually assaulted a three-year-old girl in a public library.

Immediate action needed to be taken, according to group member Beth Price, a 27-year-old mother of one rallying for change and for her children.

"My daughter is 3½, I have another one on the way," she said.

"I'd like to be able to take them to a public library and allow them to be individuals without having to worry … I have been a victim of similar things in the past, so it's a cause that's very close to my heart."

The rally is the latest instalment in the angry public reaction to the sentence handed to Shane Williams, 40, who was sentenced to 7½ years' jail, with a non-parole period of 4½ years, for assaulting the girl while her mother used a computer nearby.

The sentence included a term of imprisonment for a racist bashing that occurred last year.

The rally has been advertised across social media and will provide protesters with an opportunity to present their petition to ACT Chief Minister Katy Gallagher.

Ms Price said organisers were uncertain of the number of people attending, but were hoping for a significant number given the online support.

"It's such a big issue, especially for parents and people who know kids, so it's not really a surprise that there's so much support," she said.

A spokesman for Ms Gallagher confirmed she would be attending the event.

ACT Director of Public Prosecutions Jon White said earlier this month that his office would appeal against Williams' sentence. with Michael Inman and Christopher Knaus