Cavaliers coach Tyronn Lue said "something happened after shootaround" Thursday that led to Smith's one-game suspension.
A team source told ESPN's Dave McMenamin the suspension was from a team-related issue, and not for anything off the court. Smith was at shootaround Thursday.
Rodney Hood started in place of Smith on Thursday night, scoring 11 points in 39 minutes in the Cavs' 108-97 loss to the 76ers at Quicken Loans Arena.
LeBron James was asked after the game if Smith's absence had any emotional toll on the Cavs in the loss, and he replied, simply, "No."
Lue said Smith would return to practice Friday and would be back in the starting lineup for Saturday's home game against the Denver Nuggets.
Smith, 32, is averaging 8.3 points in 59 games (56 starts) this season.