Ernesto Valverde questioned both of Barcelona's red cards that came late on in their 4-0 thrashing of Sevilla at the Nou Camp.
First-half goals from Luis Suarez, Arturo Vidal and Ousmane Dembele put the home side in charge before Lionel Messi added a fourth as Barca remained two points behind LaLiga leaders Real Madrid.
But they ended the game with nine men as debutant Ronald Araujo and Dembele both saw red, the former for a professional foul and the France winger for dissent in a game that also had a total of eight yellow cards
Valverde said, according to AS: "It is the referee's criteria when assessing fouls. Everyone always has their opinion, but it has been a clean match.
"I am sorry for the dismissal of Araujo because it was his debut. I did not think (it was a red card) and Dembele is a mystery."
Dembele's second booking came after he reportedly said something to the referee.
Valverde is unaware what was said but hopes he will not be given a longer suspension, with his side hosting Real Madrid in a fortnight.
The Barca boss added: "It is difficult to get words from Dembele in Spanish. I haven't talked to him but I don't think it's too long a suspension."
Messi's goal was his first of the season in his fifth appearance in all competitions.
Valverde said: "Leo grabs goals and when he finds form he will score more, but it is good for us that there are other players who score goals."
Sevilla head coach Julen Lopetegui felt his side failed to take advantage of some early chances.
"We have faced (the match) with a lot of ambition and personality," he said on Sevilla's website.
"The first 35 minutes were totally ours with many chances, but in such a scenario when you don't score the law of football happens.
"We were very good, but the first goal has done us a lot of damage.
"Now it is time to analyse the game and take advantage of this break to reset."
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