LeBron James Rips Browns Fans For Booing Deshaun Watson After Injury, 'LAME AF'

LeBron James is pissed off at how Browns fans reacted to Deshaun Watson getting carted off the field on Sunday ... saying it's "LAME [as f***]" to boo someone when they're injured.

The controversial Cleveland quarterback suffered a potential season-ending ailment right before halftime in the Browns' 21-14 loss to the Cincinnati Bengals ... and as he was being taken to the locker room, the home crowd released a mixture of cheers and jeers.

King James -- who has been on both sides of the spectrum with Ohioans thanks to his departure for the Miami Heat in 2010 -- clearly took issue with how Browns supporters reacted ... going to X to tee off on the fanbase.

"Cleveland Fans!" the Lakers superstar said. "Yall know how much we’ve been thru throughout the years both good, bad and indifferent. With that being said booing anyone that’s down with an injury let alone your own player is LAME AF!!"

While it's no secret many members of the Dawg Pound were begging for Watson to get benched as he struggled under center ... some fans used the moment to voice their displeasures with the guy due to his off-field issues.

James wasn't alone in his stance, though ... as Cleveland players expressed their displeasure with Browns backers after the game -- including Myles Garrett and Jameis Winston.

The backup QB gave a passionate reaction during an interview ... saying he's "very upset" with how people handled the incident.

As for Watson, he was visibly emotional as he was whisked away to get checked out ... putting a towel over his head and appearing to tear up.