"I let my temper get the best of me," Bridges told reporters in a post-match press conference after the 132-103 loss for his team, the Charlotte Hornets.
"That was definitely the wrong thing to do by throwing my mouthpiece."
He said he was targeting an Atlanta Hawks fan, adding: "I was aiming for the guy that was screaming at me and ... it hit a little girl.
"That's definitely unacceptable on my part, and I take full responsibility. I'm ready for any consequence that the NBA gives me.
"That's on me. That's out of character for me. You've been around me, you know I don't act like that or never flash out like that. So that was definitely wrong, a lot of emotions.
"Hopefully I can get in contact with the young girl and sincerely apologize to her."
A sore defeat
The Hornets forward amassed two technical fouls and was eventually ejected in the fourth quarter after he passionately protested a goaltending call.
While Bridges was walking off the court and towards the locker room, a Hawks fan appeared to yell in his direction and the player responded by throwing his mouthguard, which reportedly landed on a young spectator.
Bridges could face additional penalties for his behavior, according to the official NBA website.
The Hornets haven't made the playoffs since 2016. They showed promise at the end of the first half, earning 29 points against their opponents' 28. But Hawks forward De'Andre Hunter wrapped up his team's victory by smashing a third quarter surge, after rising point guard star Trae Young netted 24 points.
By the end of the game Hunter had achieved 22 points, while Danilo Gallinari and Clint Capela finished with 18 points and 15 points respectively. Bogdan Bogdanovic and Kevin Huerter also made sizeable contributions to the Hawks' win, scoring 13 points each.