"He and I met yesterday for an extended period of time," Tomlin said after Wednesday's practice. "I'll leave the nature of that conversation between us. There was discipline involved for his missed meeting on Monday."
Tomlin did not field questions. Brown is scheduled to address the media Thursday.
Tight end Jesse James said Brown practiced fully Wednesday and is in the game plan for Monday night's game against the Tampa Bay Buccaneers. Cornerback Artie Burns said the discipline is "between him and the coach," but said the team supports Brown and expects him to play.
Brown was a no-show to Steelers headquarters the same day he tweeted "Trade me let's find out" to a former Steelers public relations staffer who posted that Brown wouldn't be the same player without quarterback Ben Roethlisberger.
Defensive end Cam Heyward, one of four team captains, said he spoke to Brown this week but will keep details private. "I don't make those decisions but, shoot, I'd be a little surprised if he's not there [Monday night]," Heyward said.
Brown also got into a confrontation with offensive coordinator Randy Fichtner on the sideline during Sunday's 42-37 loss to the Kansas City Chiefs, which dropped the Steelers to 0-1-1 this season.
Roethlisberger said he has spoken to Brown and is not taking his actions personally.
"He's the best in the world," Roethlisberger said of Brown. "When you're the best in the world, you want to help participate, you want to win football games. We're all a little frustrated because we're not winning right now."
Brown was clearly upset with his role during Sunday's loss to the Chiefs and did not address the media after the game. On Monday, he didn't show up to work for what agent Drew Rosenhaus called a "personal matter" in a statement.
Roethlisberger said Wednesday from his locker that Brown's tweet wasn't directed at him, and he isn't concerned about Brown's behavior as of now.
"AB is a very passionate football player. I think we all know that, the fans know that," Roethlisberger said. "That's what makes him special, is his passion for this game and the passion to be great. We're not going to want to take that away from him.
"When he gets frustrated in games, just tell him to stay with me, talk to me, communicate with me. ... If I missed you on something, if you're getting open and I didn't see you, let's just talk and communicate. He does a great job of doing that."
Brown leads the league with 33 targets, but none of his 18 catches has gone for more than 22 yards. Brown couldn't break loose Sunday, with 67 yards on nine catches despite Roethlisberger's 452 passing yards and three touchdowns.
Brown was seen walking off the field by himself, head down, while the rest of the offense celebrated a Roethlisberger touchdown scramble with 1:59 left.
Brown and Roethlisberger have become one of the most potent duos in NFL history; Brown has five straight 100-catch seasons.
Brown's antics and running back Le'Veon Bell's absence over the franchise tag have placed a spotlight on the Steelers' locker room culture under Tomlin. But Roethlisberger points to organizational stability -- mainly, the team having just three head coaches since 1969.
"I love this franchise, this organization, and it starts at the top with the Rooneys," Roethlisberger said. "Art is a great leader for all of us. There's a reason there have only been a few coaches here. If there were issues at that level, we'd have a lot more turnover there. I think at some point, the coaches have to do their thing, but it also comes down to players doing theirs."
That could include staying off social media, as Roethlisberger said he does. On occasion, he has told teammates not to address "trolls or whatever" who bait players into responses.
"It's just about being about your business, about your job, going out to practice, to meetings, being on time, and making sure you hold guys accountable," Roethlisberger said.