Chelsea have fined Kepa Arrizabalaga one week's wages for refusing to be substituted in Sunday's EFL Cup final defeat to Manchester City.
Kepa twice required treatment during extra time at Wembley, with Willy Caballero - Manchester City's shoot-out hero in the 2016 final - prepared to come on.
Sarri appeared to be furious as Kepa defied his order to come off, with Caballero left confused on the sidelines during a long delay.
The Chelsea boss explained in his post-match news conference that it was a "misunderstanding", saying he understood the apparent injury to Kepa was more serious than the Spaniard felt.
The Italian reiterated in Chelsea's statement that there was a mix-up and Kepa has since apologised to Sarri and the rest of the team, though that has not spared him from an internal sanction issued by the club, rather than the coach.
"Kepa and I have spoken about the incident. It was a good conversation," Sarri told Chelsea's website. "There was a misunderstanding yesterday [Sunday], but he realises he made a big mistake in the way he reacted.
"He has apologised to me, his team-mates and the club. It is up to the club if they want to discipline him according to the club rules, but for me this matter is now closed.
"The team performance as a whole was extremely positive and it is a shame to see how this incident has overshadowed our efforts in what was a very competitive final.
"Everyone's focus is now on the next game and we must all now put this behind us."
Kepa accepts he handled the situation poorly and has asked for forgiveness, accepting "any punishment" handed down to him.
"I was very happy to play in my first cup final for Chelsea and very proud of the team performance," the Spain international said.
"I have thought a lot more about the events. Although there was a misunderstanding, on reflection, I made a big mistake with how I handled the situation.
"I wanted to take the time today [Monday] to apologise fully and in person to the coach, to Willy, my team-mates and to the club.
"I have done this and now I want to offer the same apology to the fans. I will learn from this episode and will accept any punishment or discipline the club decides is appropriate."