The NBA referees' official Twitter account apologised for a "gut-wrenching" mistake after a decisive last-minute officiating error cost the Los Angeles Lakers against the Boston Celtics.

With the score tied at 105-105, LeBron James was smacked on his shooting arm at the rim by Jayson Tatum as the Lakers star went for glory with under five seconds remaining on the clock.

The four-time MVP and four-time NBA Finals MVP would fall short with his attempted drive before the Celtics snatched a 125-121 triumph in overtime.

James, Anthony Davis and the entire Lakers bench erupted at the last-gasp call, with Patrick Beverley issued a technical foul after bringing over a camera to referee Eric Lewis to review the decision.

Davis said Los Angeles were "cheated", while James expressed confusion at the clear error and the NBA referees took to social media to apologise on Sunday.

"Like everyone else, referees make mistakes. We made one at the end of last night's game and that is gut-wrenching for us," the official account wrote.

"This play will weigh heavily and cause sleepless nights as we strive to be the best referees we can be."

The apology may prove little consolation for James, whose 41 points on Saturday in Boston proved in vain.

Defeat saw the Lakers fall to 23-27, sitting 13th out of 15 teams in the Western Conference ahead of four road games in the coming week.

Los Angeles will look to bounce back at the Brooklyn Nets on Monday without James and Davis after the Lakers confirmed the pair would be absent on the first night of their back-to-back.