Officers were called to The Pelican, in Bracebridge Drive, Bilborough, at around 9.10pm on March 5 when the man walked in and brandished the weapon.
It is believed he had previously been involved in a fight outside the venue.
One man sustained a minor injury to his hand during the incident.
PC Lewis Bullmore, of Nottinghamshire Police, said: “This was a frightening incident that could very easily have resulted in a serious injury. We have been working hard to track down the person responsible but would now like to appeal to the public for help.
“Do you know the man in this image? He is of a large build, wore blue trainers and had a chinstrap style beard. If you know who he is please get in touch with us as soon as possible.”
Anyone with information is asked to call 645 of 5 March 2023.
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