Witness say that at about 11.30pm Thursday, a dog jumped up and bit the face and throat of a man standing in the doorway of the bar.
The dog is thought to belong to a homeless man who usually lives on the street outside the bar.
Emergencies services were called, but the man only sustained minor injuries.
The bar owner told newspaper Nice Matin: “These homeless people have been hanging around outside the bar for years. Even if the police move them on, they always come back.”