Mr Nightingale said thieves had been targeting vehicles which could be easily broken into, and some vehicles had also been stolen.
"We strongly recommend people have things safely locked away and out of sight, or even better, take them with you, keep them where you can see them," he said.
"We want people to have a good experience visiting Rotorua, and the only way they can do that is by being aware of the environment and where their valuables are."
Mr Nightingale said police often covered the area but it was important for people to call them if they noticed suspicious people or behaviour.
"Generally when these things start to happen, we put on extra force and we usually have a guy nearby, so people just need to let us know."