Senior Sergeant Byron Reid said officers had observed an increase in large groups of young people gathering in the city over recent weekends.
Reid was concerned that young people were being given alcohol by older teenagers or young adults and engaging in disorder and antisocial behaviour.
"Please take some time to talk with your child ... about where they are spending time, who they are with and the potential risks of being in the city late at night," he said.
"If they are heading into town, it's important to know their plans, ensure they are with safe and responsible people, and have a plan to get home safely."
If police believed a young person's safety or well-being was at risk, they would be returned home, Reid said.
"Please also let your young person know that police are there to keep them safe, not to get them into trouble.
"It's also important to remember that if you are providing alcohol, it needs to be given and consumed in the home environment and only to people legally in your care - not anyone else's."
