Guests at a wedding party in New Athos, a Black Sea town in the disputed Georgian republic, fired two flares and gunshots, which the crew interpreted as warning of potential attackers in the nearby waters, a crew member told RIA Novosti.
The Azov vessel was on its last day of combat duty in the area when the incident occurred late on Sunday.
"The ship was put on immediate combat alert, and the main engine was started up. We were about to go to the high seas but first we had to receive authorization to open fire," he said.
Explaining the incident, an officer on duty at the port said: "This is a wedding. It is our custom. We are now working to calm them down."
The ship returned to its naval base in Sevastopol later on Sunday evening.