The team announced the decision on Adebayo and Dragic about two hours before tipoff inside the NBA bubble near Orlando, Fla. Adebayo was ruled out with a neck injury, while Dragic is out with a torn left plantar fascia.
The injured stars arrived at the arena as longshots to suit up. Adebayo had been trying to persuade coaches to allow him to play but ultimately was ruled out again.
Both were injured in the Heat's Game 1 loss to the Los Angeles Lakers, and neither played in Miami's Game 2 loss Friday night.
"The injury bug hit us at the wrong time," Heat forward Jae Crowder said.
The Lakers hold a 2-0 lead in the best-of-seven series. Game 4 is set for Tuesday night.