Monica Stops Fans Fighting at Concert, 'I Ain’t Singing ‘Knuck If You Buck‘'

Monica put a damper on her "Goonica" nickname, and a few fans' chances of landing more punches during a fight that erupted at her show.

The star singer was recently in D.C. for the R&B Experience Tour, and was bringing the house down with her hit ballad, "Why I Love You So Much" ... when she noticed the brawl breaking out in the stands right in front of her.

A confused Monica wondered what about her quiet storm classic could prompt people to fight and demanded they stop ... even offering to buy them a drink to cool them off.

“I ain’t singing 'Knuck If You Buck' baby, calm that s*** down,” she told the rowdy bunch, referencing Crime Mob's 2004 fight-starting record.

The bribe didn't seem to work and Monica suggested they take the scuffle outside ... and cleverly dropped her fan-favorite song "So Gone" to celebrate the fans' exit from the venue.

Monica has long been accused of having a thug side ... and did her best to explain the nickname to Stacey Abrams and Ciara last year during election season.