The incident happened at Cavendish Street Wednesday, November 15.
Detective Sergeant Wilson said: “It was reported that a male, armed with a tyre iron, entered the shop at around 7.55pm on Wednesday night.
“He threatened staff before a member of the public intervened and he left the shop empty handed.
“He was seen leaving the area in a blue hatchback car with another male on board.
The male who entered the shop is described as being approximately 5’10”, wearing grey tracksuit bottoms, a blue puffa style coat with a fur hood and red scarf over his face.
“I would appeal to anyone who witnessed the incident or anyone with any information which could assist us with our enquiries to contact detectives at Musgrave on 101 quoting reference number 1246 of 15/11/17.
“Information can also be given anonymously through the independent charity Crimestoppers on 0800 555 111.”