Whangarei police communications officer Sarah Kennett said when officers turned up to disperse the crowd some of them took exception and threw rocks and bottle.
No officers were struck by the missiles.
"It was only a couple of young people that decided to throw bottles and rocks. The police were not pelted by the group," Mrs Kennett said.
"It wasn't a major disorder situation at the end of the day."
She believed that the group had gathered as a result of text messages, twitter and Facebook but could not confirm if that was actually how the crowd had gathered.
Police say there were no gang issues or connections with the gathering.