The attack happened at residential premises at the Queens Park area of Saintfield in the early hours of Thursday, December 27.
Detective Sergeant Bell said: “At around 00:40 am it was reported that three males approached a property in the area, with two men armed with bars and one man armed with a hatchet.
“A male occupant inside the property who opened the door for the offenders was struck on the head by the man armed with the hatchet.
“He received a small cut to his head that was not believed to be serious.
“One of the males is described as being 6”0 in height with short dark hair and wearing a dark hooded top and tracksuit bottoms.
“The second male is described as being 5”6 tall, of heavy build with a navy hooded top and tracksuit bottoms.
“The third male is described as being 5”8 in height, slim build and wearing dark clothing.
“Enquiries are continuing and we would appeal to anyone with any information or who saw anything suspicious in the area to contact detectives on 101, quoting reference number 86 27/12/18.
“We are particularly keen to speak to anyone who saw a dark coloured Renault Clio with ‘R’ plates in the area at the time of the incident.
“Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime.”