Kyle Kuzma stabbed Cavs fans in the heart with a game-winning shot on Wednesday ... and then twisted the knife with his postgame comments, saying, "Without LeBron (James), Cleveland wouldn't be s***."

Kuz's trey with just over 10 seconds left in the 4th quarter helped secure the 97-94 win over the Wine & Gold ... and after the game, he blamed Cavs fans for motivating him to knock down the shot in the clutch.

"I was just ready, I was ready for it," Kuz told reporters. "Plus, there was some hecklers during the game, talking to me. It was their fault, really. It was their fault."

Kuz -- who won a championship with the Lakers in 2020 -- points out a few fans in particular who had a sign that read, "LeBron won Kuzma his ring" ... and he didn't hold back when addressing them directly.

"I said, 'Without LeBron, Cleveland wouldn't be s***' ... so, they chose violence and I just kept going. So, thank you guys, I appreciate it."

In fact, Kuz rubbed it in fans' faces after the W ... taking a Sharpie and autographing the sign that inspired him to nail the dagger at the end of the game.

Of course, it's no secret the Cleveland Cavaliers organization owes everything to LeBron for ending the city's 52-year drought ... but considering Kuz averaged 8.5 points, 2.8 rebounds and 0.5 assists in the Finals for the Lakers, let's not pretend he doesn't also owe a ton to the King.

Aside from the jab, the Cavs seem to be showing promise for the first time in a post-Bron era -- they're currently 7-5 with guys like Jarrett Allen, Evan Mobley and even Ricky Rubio balling out so far this season.