TORONTO — J.R. Smith’s act is starting to wear thin on the Knicks’ coaching staff.

Coach Mike Woodson, Smith’s most ardent supporter, ripped his sixth man and the club in general for losing their composure in Wednesday’s 125-91 disgraceful loss to the Pacers.

Smith attempted to bait Indiana’s Lance Stephenson into a fight at the end of the first half, jawing at him as the seconds ticked down. Smith continued his harangue and Stephenson finally answered back with the two players drawing double technicals.

Smith then got ejected in the third quarter after committing an offensive foul against Stephenson. He made a remark to the official and made a gesture with his hand. Replays were inconclusive as to whether or not Smith had given the middle finger.

Asked if he had spoken to Smith about his behavior, an angry Woodson said: “I’m not happy about how we played and how we carried ourselves professionally on the basketball court. We can’t do that. I’m not going to tolerate that. I’m just not.’’

Smith also had an incident with the Knicks’ mild-mannered assistant coach, Herb Williams. In the first half, Williams and Smith exchanged angry words on the bench during a timeout. After the game, Williams’ anger seemed to carry over.

As Smith talked to a media scrum, Williams walked over and ordered Smith to take his headphones off while he was addressing reporters. Smith’s headphones were draped around his head. Smith took them off and Williams shook his head in disgust as he walked away.

Smith was not the only hothead in Indiana. Raymond Felton elbowed Jeff Prendergast and picked up a flagrant foul during the rout. Tyson Chandler lost his cool at the officials after Tyler Hansbrough laid a hard foul on him.

Amar’e Stoudemire, after picking up his third foul, ripped off his goggles and berated the officials, picking up a technical foul. After Kurt Thomas picked up his fourth foul in six minutes, he came to the bench and cursed out a heckling fan.

It is a bad trend for a club with championship aspirations. In a few losses this season, most notably against Memphis, Chicago and Boston — the Carmelo Anthony/Kevin Garnett incident — the Knicks have flashed their hot tempers under adversity.

“We have a veteran team,’’ general manager Glen Grunwald said. “They know where they need to improve. Keeping composure is one of the things they all talked about postgame. They’re aware of what they need to do.’’

Explaining himself, Stoudemire said, “The result wasn’t to get a technical foul. But both teams being physical, I wanted to play physical and we weren’t allowed to. I felt frustrated. We wanted to play physical on our end but couldn’t quite accomplish that.’’

Anthony, who berated Smith on the court after his Stephenson tiff, said the club realizes it did wrong in every way Wednesday.

“I’ve seen guys today, guys were angry,’’ Anthony said. “Not angry but kind of upset. As a team we let ourselves down. It was kind of an embarrassment.’’