Butler was ruled out of Miami's season opener against Memphis on Wednesday for what the team called "personal reasons.''
Butler was with the Heat Wednesday morning for their game-day shootaround and told the team around midafternoon that he wasn't going to be able to play.
Heat coach Erik Spoelstra said "everything's fine'' and that there is no reason for concern.
Butler was a big offseason acquisition for the Heat this past summer, agreeing to a four-year deal in a sign-and-trade with Philadelphia.
The Heat were also without guard Dion Waiters, suspended one game for conduct detrimental to the team, and forward James Johnson -- still out because of a conditioning issue that kept him from training camp and sidelined for all five of Miami's preseason games.
The Heat ran away in the fourth quarter to beat the Grizzlies 120-101.
The Associated Press contributed to this report.