It happened at about 3 pm on Tuesday outside the Scotmid store in Lochside Road.
The white spaniel was tied up outside the shop and bit the 21-year-old man on the knee.
It was taken away afterward by a blonde woman, who police say may be unaware of the incident.
Officers are carrying out inquiries and want to trace the woman or speak to anyone with information. PC Ross Jack can be contacted via the 101 number.