Smart did not reference the officiating during a media session with a group of reporters immediately after the game, but he was later asked about the difficulties in defending Houston star James Harden.
Smart decried some of the whistles against the Celtics in an interview with the Boston Globe.
"When you're playing a guy like that who gets those types of calls, it's pretty much like you're playing in foul trouble," Smart told the Globe. "You've got to play really certain. You have to be really solid. You can't really play the defense that you want, because you know nine times out of 10, he's going to get those calls. It doesn't matter whether your hands are up or not. He still gets them. We saw that here tonight a few times, and we've seen that every other game.
"He has a way of using his hands, grabbing us, pulling us into him and drawing those fouls. He's been doing it for a long time. He gets the benefit of the doubt."
Celtics swingman Jaylen Brown found early foul trouble while trying to defend Harden on Saturday. On one whistle, Brown appeared to get hit in the face on a Harden drive. Early in the third quarter, Harden appeared to push off Brown in order to receive a pass at the top of the key.
Brown got whistled for his fourth foul and then got a technical for arguing how Harden's shove had sent him to the floor.
"It happens all around the league," Smart told the Globe. "You get certain players who get calls that other guys just wouldn't get. We all know the rule. We all understand it. Superstars are going to be superstars. We get it. It is what it is. We've just got to play."
Smart, who was celebrating his 24th birthday Tuesday, was on the right side of the referees' whistles in December when Harden was called for two offensive fouls in the final seconds of Boston's comeback win.
After that December meeting, Harden vented about the officiating, including the use of only two game officials after one was injured in pregame warmups, but was not fined for his comments.
"First of all, I want to know, how do you only have two officials on a national TV game? That's the first question," Harden said in December. "A lot of grabbing, a lot of holding. I mean, how else am I supposed to get open? Guy has two arms wrapped around my whole body."
Added Harden: "It's just tough. You can't have two officials in a professional game. There's a lot of no-calls that need to be called, because that changes the dynamic of the game."