Police say that at 7:20 pm officers received a report a male had entered the premises with what is believed to have been a knife and approached a staff member.
The assailant then made off on foot, empty handed.
No one was reported injured.
The suspect is described as 5’9’’ tall, of medium build and was wearing a black puffa-type jacket and a white hat. He was described as being aged in his mid-20s.
Detective Sergeant Rory McPhillips said: “I want to appeal to anyone who was in the area and saw what happened, or saw a male matching this description acting suspiciously around this time to contact us quoting reference number 1072 of 11/09/18.
“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.”