A Christchurch mother's trying to make her autistic son's favourite skatepark safe after she was punched in the face herself by one of his bullies.

Erica Godfrey approached a boy who had pushed her 14-year-old son, Isaiah, at Thomson Skate Park in South New Brighton.

She pleaded with the boy to stay away from her son, who has autism, ADHD and a rare tumour in his throat.

She says she couldn't believe what happened next.

"He basically hit me quite hard in the face, which gave me a shock.

"My instant reaction was to burst into tears and run away, but I thought for my son, I need to try and talk it through with this boy and get it through to him to leave my son alone."

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She's said it's not the first time she's heard of violence at the park.

"Probably half the locals can probably tell you things that have happened at Thomson Park."

She is asking the council to install security cameras and lights to make it safer.

Godfrey says the teen who hit her was referred to Youth Aid, where she hopes he'll get the help he needs.