Asked whether the person involved had threatened anyone in the vicinity, the spokeswoman said: "No indication they were being threatening - just that they were noticed by others to have it in their possession."
The incident comes almost a week after a shooting incident at another downtown Auckland bar - Dr Rudi's Rooftop Brewing Co - at the Viaduct.
Police were called there about 2.45am in the early hours of last Sunday after shots were fired into the foyer ceiling.
Police said a "brief altercation" broke out among a group of people outside the bar before someone pulled out a gun. They had earlier been removed from Dr Rudi's.
No one was injured in the incident, but other punters who were there took cover - some reportedly hiding under tables - after the shots were fired.
A 25-year-old man has been arrested and will face a number of firearms-related charges as a result.