James Harden has been fined $100,000 by the NBA for saying he would not play for the Philadelphia 76ers while president Daryl Morey was in charge.
The guard called Morey a “liar” in an interview after reports the 76ers had ended talks about trading him.
Harden, 33, was reportedly keen to join the LA Clippers before talks faltered.
The NBA said the fine was for saying “he would not perform the services called for under his player contract unless traded to another team”.
In response, the National Basketball Players Association said: “We respectfully disagree with the league’s decision to discipline James Harden for recent comments he made, which we believe do not violate the rule against public trade demands.
“We intend to file a grievance and have the matter heard by our Arbitrator.”
The fine relates to comments made by Harden on 14 and 17 August, when he in effect threatened to strike by refusing to play for the 76ers over their refusal to trade him.
The NBA added: “The league’s investigation, which included an interview of Harden, confirmed that these comments referenced Harden’s belief that the 76ers would not accommodate his request to be traded.”
Harden made the controversial comments about Morey on 14 August during a promotional event in China.
He said: “Daryl Morey is a liar, and I will never be a part of an organisation that he’s a part of. Let me say that again: Daryl Morey is a liar, and I will never be a part of an organisation that he’s a part of.”
Harden said in subsequent media interviews that Morey had gone back on a promise to trade him quickly earlier in the off-season.
According to ESPN, talks between the 76ers and the Clippers broke down because of the demands set by his current team, who are expecting the player to return for a training camp in September.
Harden was named the NBA’s most valuable player (MVP) in 2018 while playing for the Houston Rockets, where Morey was general manager.
The pair’s relationship was a key factor in Harden moving to Philadelphia in a trade which sent Ben Simmons to the Brooklyn Nets.
Harden helped the 76ers, alongside reigning NBA MVP Joel Embiid, to last season’s Eastern Conference semi-finals, where they lost to rivals Boston Celtics after blowing a 3-2 lead in the series.
The regular season starts on 24 October, with the 76ers playing the Celtics in their first pre-season game on 8 October.