Luka Doncic thinks it's RIDICULOUS the refs ejected his teammate Kristaps Porzingis for that NOTHING-BURGER of an altercation during Monday's playoff game.

... and LeBron James agrees!!

The Dallas Mavericks big man got the heave-ho for confronting Marcus Morris during an incident in the 3rd quarter.

KP was stepping up to defend Luka's honor -- after Marcus had gotten physical with him earlier. Nothing crazy. No punches. Just some minor shoving.

Still, Porzingis was tossed as a result -- and it pretty much spelled doom for the Mavs; chances at winning that critical Game 1 playoff game.

In fact, without KP, one of Dallas' best and most important players, the Mavs lost 118 to 110.

After the game, Luka not only defended Porzingis, he called out the refs in the process.

"I knew KP had my back. He did it for me, he did it for his teammate. He had my back."

"I don’t think it was fair to get him out of the game -- especially in the playoffs.”

"But you know, they decided -- so we had to play without him, which was tough."

Doncic wasn't the only one who was pissed about the bad officiating -- LeBron James and Dirk Nowitzki spoke out too.

"Man that was BOGUS AS HELL MAN!!!! Cmon man." James said on Twitter.

Nowitzki added, "The ejection is super soft."

Doncic carried the team once KP was ejected, scoring a game-high 42 points -- a record for the most points by any player in their first playoff appearance in NBA history.

Bet he would rather have the "W" instead though ...