Messi, 38, and teammate Jordi Alba have both been handed a one-games suspension for skipping MLS All-Stars 3-1 win over their Liga MX counterparts.
The legendary Argentinian will now miss Inter Miami’s next home game against FC Cincinnati on Saturday, something Mas says he’s “extremely upset” about.
Mas claimed it was the club’s decision to allow the two players not to play in the game, keeping their fitness in mind ahead of the rest of the MLS season.
“Obviously it was not a positive reaction,” Mas said of the players' response to the sanctions. “They want to compete. They want to play games. That’s what they’re here for: to play and win.
“They understand the magnitude of tomorrow’s night’s game. So the reaction was exactly as expected out of two competitive players who don’t understand the decision.
“Who don’t understand why not attending an exhibition match leads directly to a suspension. The rule is what it is, but they don’t understand it.”
Mas said he was "hopeful" the decision won’t impact ongoing contract negotiations with Messi, who's current deal expires at the end of 2025.
“He’s very upset, extremely upset today, as expected,” Mas said of Messi. “I’m hopeful it doesn’t have an impact long-term. Will it have an impact initially, in the players’ perception of how the league rules work? Absolutely no doubt.”