Chalmers, a regular target of criticism from his Heat teammates, committed a turnover, missed a three-pointer and committed two fouls during a two-minute span of the third quarter. The second of the two fouls came on a Paul George three-point attempt, leading to three free-throws.
Here's an animated look at James' outburst, which ended quickly as teammates intervened.
TNT's cameras apparently caught James saying "My bad" to Chalmers during a fourth-quarter stoppage of play, and both addressed the confrontation on Twitter after the game.
"I love Mario Chalmers like a blood brother!" James wrote. "I was wrong and apologized to him! We good and will always be good. I ride [with] him any [and] every day."
Chalmers replied: "All good big bro. At the end of the day we brothas and nothin' gonna change that."
Heat coach Erik Spoelstra pulled Chalmers from the game for good midway through the third quarter. Chalmers finished with four points (on 1-for-5 shooting), five assists and two turnovers in 19 minutes.
The exchange did not stand in the way of Miami's comeback victory. James tallied 24 points (on 8-for-14 shooting), nine rebounds and seven assists, while Dwyane Wade scored a game-high 32 points (on 15-for-25 shooting) and added three rebounds for the Heat.
Paul George led the Pacers with a team-high 25 points (on 8-for-16 shooting), eight rebounds and six assists in a losing effort.