The league fined Irving $25,000 for "using inappropriate language when responding to a fan" the NBA said in a press release.
After practice on Saturday, Irving acknowledged that he did say something to a fan and that he had a conversation with the league regarding the incident.
The NBA fined Pelicans center DeMarcus Cousins $25,000 for language he used toward a fan late in a loss to Memphis on Wednesday night in the season opener. "Excuse the kids at home and you move on".
The Cavaliers' trade of Irving to the Celtics for guard Isaiah Thomas, forward Jae Crowder, rookie centre Ante Zizic and two draft picks in August was one of the league's blockbuster deals of the offseason.
Irving was key to Boston registering the win, filling the stat sheet with 21 points and six rebounds.
"Hell no", said Irving. The video went viral on social media.
Irving took responsibility for a profane outburst directed at a fan in Philadelphia who yelled at him and referenced LeBron James during Friday's game against the 76ers.
"At the end of the day, we're human", Irving continued. Being with a young team like we have here and staying composed, handling that before we go in the locker room and addressing what we have to do in the locker room and going out and handling business and getting the W. That's really the only thing that matters to me. That was like a pat on the back. "There's a right and wrong, and if you're in the wrong, you have to own up to it".