Police have released CCTV images of four men who broke into a massage business at Seacombe Gardens in Adelaide's south and assaulted three women.

The men, who wore dark clothing and covered their faces, entered the premises in Morphett Road about 1:30am on Friday.

Police said the men assaulted the women, demanded cash and also confronted a man in a granny flat at the back of the property.

One of the women was treated at Flinders Medical Centre for a laceration to her head.

The men are believed to have left the scene on bicycles.

Police said they do not believe the attack was random and that the men specifically targeted the business.

They stole cash and personal property, including jewellery.

Superintendent Lyn Dunstan said: "Irrespective of the type of business targeted during this incident, this type of violence in our community will not be tolerated by police."

Anyone who can help the investigation is asked to contract Crime Stoppers on 1800 333 000 or online.