A spokeperson said police was called at 9.10pm in relation to incident at Traffers Bar in Hokonui Dr.
Detective Sergeant Scott MacKenzie said a man wearing a mask and holding a knife entered the bar about 8.45pm and demanded cash from the bar manager.
The offender could not access the till and so fled the scene on foot, Det Sgt MacKenzie said.
"No money has been taken."
"Victim Support are assisting the victim who was deeply shaken by this experience. No one was injured in the incident."
Police said they were checking the security cameras and inquiries are ongoing to locate the offender.
Police believe he headed west onto Trafford St and possibly across a field at the end of the street, Det Sgt MacKenzie said.
"Gore Police would like to hear from anyone who has information that could help identify the offender."
Anyone with information is asked to contact Gore Police on 03 203 9300.
Information can also be passed on anonymously through Crimestoppers on 0800 555 111.
