He was described as being possibly Maori or Pacific Island, in his 30s and about 175cm tall.
"This was a particularly frightening experience for the victim and we are very keen to hear from anyone who may have witnessed the incident or seen other suspicious behaviour in the area.
"If you have seen a vehicle or person matching this description behaving suspiciously, please call us immediately, even the smallest piece of information may prove valuable to help ensure this man is held to account for his actions," Willis said.
If you have any information contact Willis on (09) 820 5776 or call Crimestoppers anonymously on 0800 555 111.