It was reported that two males, one armed with a knife, entered the premises at around 10.20 pm on Saturday night.
They threatened staff members and demanded money.
No money was handed over however, and the two males made off from the scene on foot.
Detective Inspector Richard Thornton said: “ Officers are working to identify those involved in the incident and enquiries are currently ongoing.
“I would appeal for anyone with any information to contact detectives at Musgrave on 101 quoting reference number 1215 07/01/17.
“Information can also be given anonymously through the independent charity Crimestoppers on 0800 555 111.”