A Canberra mother urinated on in front of her children at a music festival has blasted police and security guards who laughed and allegedly dismissed her complaint.

Joana Perkins attended the Canberra leg of Groovin' the Moo, held in Bruce on Sunday, so that she could keep an eye on her 15-year-old son, Sam, and his friends. Being an all-ages event, she also brought her daughter Ema, nine, along for the day.

In a Facebook post to ACT Chief Minister Andrew Barr, Ms Perkins expressed her outrage with the allegedly inadequate response of private security firm ISEC after she was urinated on in the crowd.

"I notice a bloke behind me and my sixth sense picked up he may have been 'fiddling' with his penis," Ms Perkins wrote.

"The feeling of warm liquid running down my leg confirmed the very drunk bloke had decided to urinate on my legs."

She said she turned and grabbed the man by his arm, keeping him restrained until she was able to get assistance from a security guard.

"As my daughter was now pretty upset and I had urine down my leg, we decided it was time to leave. Heading out of the door we noticed the two security guards laughing. They patted the drunk guy and let him go."

After attempting to complain about the inadequate response by the security provider, she claims her complaint was flippantly dismissed.

"The female security supervisor proceeds to tell me that I am the one with the problem, bringing children to GTM (it is an all ages festival). Sam is furious. As am I. I was there to keep an eye out for the kids (and after this incident I believe it is more critical than ever)," Ms Perkins wrote.