Two people came across the one-metre-long reptile while walking in Heidelberg Heights about 8:30pm local time on Monday night.
It was "sitting quietly" on a footpath in the front yard of a business on Waiora Road, police said.
Officers were called to the scene, but decided to hand the case over to the experts and a reptile catcher came to help.
The catcher will look after the crocodile until staff from the Department of Environment, Land, Water and Planning can collect it, police said.
It's not known where it came from or how it ended up at the business, which was closed for Christmas.