According to gossip website TMZ.com, the 48-year-old actor was caught on camera yelling: "How we doing?... Lying bunch of f**got a**holes, how we doing?" while introducing a number of musical acts on stage to perform at the bash, including rocker Slash.
Charlie, who is a partner in the bar, has since apologized for the comment, saying: "I meant no ill will and intended to hurt no one and I apologize if I offended anyone."
He also attempted to jokingly brush off the insult, by insisting: "I meant to say maggot but I have a lisp."
Before taking to the stage, Charlie was said to have been partying hard at the event and was spotted kissing a number of girls, shaking hands with guests and taking pictures of everyone.
Guests at the bash included Los Angeles mayor Antonio Villaraigosa and Dr. Robert Huizega from 'The Biggest Loser'.