Initial information suggests around 6.30pm a woman was walking past a soccer club on Ben Nevis Street when she was assaulted.
The man is described as being aged 30-40 with a chubby build. He was wearing shorts and a long-sleeved running shirt and has short dark hair.
Anyone with information is urged to contact Mackay Police on 4968 3460 or Crime Stoppers.
Anyone with information which could assist with this matter should contact Crime Stoppers anonymously via 1800 333 000 or crimestoppers.com.au 24hrs a day.
Crime Stoppers is a registered charity and community volunteer organisation working in partnership with the Queensland Police Service.
For all non-urgent police reporting or general police inquiries contact Policelink on 131 444 or www.Policelink.qld.gov.au 24hrs a day.