Trey Songz -- Catfight Breaks Out Over R&B Singer

Trey Songz was at the center of a nightclub brawl this week in New York City, but it was the kind Kramer would approve of ... it was a CATFIGHT!!!

Sources inside the Juliet Supper Club tell TMZ ... a group of girls were trying to get close to Trey on Monday night, and his date for the evening was not pleased. We're told the girls exchanged words and someone from the group tossed a drink on Trey's girl ... causing a melee.

The owner of the club, Barry Mullineaux, tells TMZ his security team jumped right in tossed the group of girls from the club. Police were not called.