On 30 December 2019, officers imposed a 48-hour closure notice on the Boat House Pub, formerly known as the Tower Hotel, on Stryd Fawr, Pwllheli.
Police said it had no confidence in the management's ability to prevent, or respond to, further violence.
Inspector Matt Geddes said: “This is not a decision taken lightly but is necessary to ensure public safety in the town over the new year period.
“We will be working in partnership with Gwynedd Council moving forward to ensure significant improvement if the premises are to continue trading.”
A spokeswoman for North Wales Police told the BBC that an officer had been punched on the side of the head on 21 December.
This was after responding to calls regarding a man leaving the pub who became aggressive with members of the public.
According to the BBC, he also tried to head-butt another officer and resisted arrest.
There was also an assault outside the pub on 27 December where a drunk customer attacked another customer and caused serious facial injuries, which required hospital treatment.
Geddes said: “Following events of violence over the Christmas period resulting in injury to police officers and members of the public, and subsequent interaction with premises management, we have been left with no confidence in the ability or willing of the management to effectively prevent or appropriately respond to further violence or other criminal acts on or associated with the premises.”