The Sunday afternoon melee broke out the day after the $900,000 Holborn Park attraction opened amid positive speeches, ribbon cutting and community fanfare.

Unconfirmed reports suggest a 20-year-old man was at the centre of a disagreement that began about 4pm and grew into a brawl as more people "jumped in".

Lake Illawarra Police received multiple calls from onlookers.

Albion Park mum Shannon Thompson was driving along Northcliffe Drive with her family when she noticed "groups of young people just thumping each other".

"They were all spilling onto the street, cars were just stopped on the road because they couldn't get through," she said.

"We had to stop. My husband wound the window down and yelled at them to pull their heads in. I told him to keep driving - it freaked me out.

"I've not ever seen anything like it before."

Mrs Thompson said she noticed a group "laying into" a man, aged about 20.

"My son, when we drove off, said 'there were grown men punching each other'."

Police arrived to find the fighters dispersing. NSW Ambulance paramedics were initially called, then told they were not required.

Sergeant Jason Harrison said police were not investigating the matter.

"No one has come forward as a victim," he said.

A spokesman for Wollongong City Council said anti-social activity at the park should be reported to police, but noted the attraction had been the site of happier scenes for the rest of the weekend.

"Many hundreds of skaters, families and local champions enjoyed the opening of the Holborn Park Skate Plaza in a friendly and enjoyable atmosphere on Saturday," he said.

"Staff who visited the site on Sunday also reported that there were many skaters and families enjoying the skate plaza in a friendly and co-operative manner.

"Council regrets any anti-social behaviour."