Murphy said as well as drinking some youth were starting fights and were unsupervised.
"When they are not being watched by an adult they don't have any boundaries, some of these kids are turning up in gang colours."
While he said 99 per cent of people who attended Glo Festival were law-abiding it was the kind of event that attracted young people.
"There is a small percentage of mainly young people who seem to be intent on causing trouble."
It was the behaviour of that small group who were most time-consuming and resource intensive, he said.
For Lakeside he said the police aim was the same as for any event.
"We want it to be crime free, safe and secure for the public to attend.
"We will work with our partners and anyone within the community who can help."
Rotorua police crime prevention manager Brendon Keenan said police were considering a range of measures for the Lakeside concert.
"We're looking at a range of options, including better lighting, age restrictions, behavioural expectations, signage and better supervision of young people.
"We can't just throw all our resources at events, we have to balance it out with other strategies."
Lakeside Concert Charitable Trust chairman Ian Edward said organisers were happy to have a conversation with police about their suggestions and planned to meet with them next week.
He said they would take on board the reported issues from Glo Festival and would take the necessary steps to ensure Lakeside was a safe event.
"This is a community event, we aren't paid to organise it, the last thing we want is any problems.
"We want it to be memorable for all the right reasons."
Rotorua Lakes Council arts and culture director Stewart Brown said overall Glo was a success, with the majority of the crowd well behaved.
"We were aware police dealt with a handful of youths at the venue regarding their behaviour but were unaware of any issues with children and have received no official complaints. The event has always been an alcohol-free event."
Glo Festival, like Lakeside, was targeted at families and had been well attended each year with great support from police and few problems, he said.
This year's festival attracted about 15,000 people, about 5000 more than in previous years.
"A debrief, which is common practice after events, will include police and we will discuss any potential changes or improvements needed to ensure Glo remains a fun, family-friendly event."