It happened at a TSB bank on Ellamsbridge Road on Friday 1 February.
The incident is reported to have happened just before 5pm when a man entered the bank with his face covered holding a plastic carrier bag and drinks bottle. The man pushed a customer out of the way of the counter and demanded money from the bank assistant but left empty handed.
The offender made off on foot along Ellamsbridge Road. He is described as around 6ft tall, of slim build, wearing dark clothes and a face covering.
Detective Inspector Catherine Walsh said: “We know there was a customer in the bank at the time of the incident and there would have been more people outside going about their daily business who might have seen someone acting suspiciously. If anyone has any information to help us with our ongoing investigation then please do get in touch.”
Anyone who witnessed the incident or was around the area at the time of the incident and saw someone acting suspiciously is urged to get in contact by direct messaging our social media desk @MerPolCC or by calling 101 quoting: 0657 of 1 February or contact @CrimestoppersUK anonymously