Justin Bieber seems to be pretty SHOCKED that "CSI" star Marg Helgenberger told a radio show he was a "brat" on the set ... especially because they never actually worked together.
Bieber just went to his Twitter page and without mentioning Marg by name ... said, "it's kinda lame when someone you met briefly and never worked with comments on you. I will continue to wish them luck and be kind."
As we previously reported, Marg went on a French radio show and said JB was "kind of a brat" when he guest starred on the show earlier this year.
Bieber added, "I know who i am and sometimes people r just going 2 say what they want. Keep ur head up and be the man ur mama raised. "