Griffin was ejected for his second technical with 10:43 left after scuffling with Andrew Bogut, following Warriors forward Draymond Green to the showers after they got into it at the end of the third.
"After a league review of the Clippers-Warriors game, we have come to the conclusion that Blake Griffin should not have been ejected from the game," said Rod Thorn, the NBA's president of basketball operations.
"A common foul should have been called on Griffin for initially attempting to dislodge the Warriors' Andrew Bogut and a technical foul should have been assessed to Bogut for grabbing Griffin by the shirt and wrestling with him."
With Griffin gone, the Clippers missed several key chances in the waning moments.
"If you look at it, I didn't do anything and I got thrown out of the game. It all boils down to they (referees) fell for it," Griffin said after the game. "To me, it's cowardly basketball. I don't know their intentions, but it worked. ... If I knew the answer I'd probably be in a different position. Tonight I got two technicals for nothing."
Also Thursday, the NBA fined Green $15,000 for failing to leave the court in a timely manner after his ejection.