City won the trophy for the second year in a row after a 4-3 victory on penalties following a goalless 120 minutes at Wembley on Monday (AEDT).
There were remarkable scenes in the closing stages of extra time when Kepa appeared to argue against Sarri's decision to replace him with Willy Caballero, after Chelsea's starting goalkeeper had been struggling with cramp.
Sarri reacted furiously on the touchlines, but later blamed the incident on miscommunication and made it clear he would not punish the player.
Kepa spoke to reporters after the match to say he felt the matter had got out of hand on social media and in television coverage, and stressed he was not trying to defy his head coach.
"Well, first of all, I have to say it was misunderstood," Kepa explained. "In no moment was it my intention to disobey, or anything like that with the boss.
"It was two or three minutes of confusion until the medics got to the bench, and they explained everything well. This was nothing to do with the problems I had this week, with [my hamstring], it wasn't that. And, well, it was misunderstood. Because he thought I couldn't continue, and - fundamentally - I was trying to say that, physically, I was fine.
"I know if you see it from outside, I don't know how it went out, it is not the best image. I have spoken with the boss. I think it was misunderstood. I understand that on television, on social media, they're talking about this but I am here to explain it, to say that it wasn't my intention to go against the manager. We have spoken now, and I was only trying to say I'm fine. He thought I wasn't fine. It was in tense moments, with a lot happening.
"I thought the bench felt I couldn't continue, because it was the second time I'd gone to ground. It was extra time. We'd run a lot, so [going to ground] was also a way of stopping the match. We'd had a few moments suffering, defending, so it was to stop the match and for the team to draw breath and not a moment where I was saying I couldn't continue.
"It wasn't that I was refusing to be substituted, it was a way of trying to tell the bench that I was fine."
Kepa is eager for the incident not to become the main talking point of the final, in which he felt Chelsea competed well against the Premier League champion.
"I don't think it has to be the major act of this final," he said. "I understand we played a good level against one of the best teams in the world. We were close to winning, obviously we're sad that we didn't, and I think the team needs to continue playing like this, because we've shown we can compete against the best teams. Among the negatives, we have to take the positives."
Kepa then released a statement via Twitter to underline his version of events, saying: "I regret how the end of the match has been portrayed. At no time has it been my intention to disobey the coach or any of his decisions.
"I think everything has been misunderstood in the heat of the final part of a match for a title. The coach thought I was not in a position to play on and my intention was to express that I was in good condition to continue helping the team, while the docs that had treated me arrived at the bench to give the message.
"I feel the image that has been portrayed was not my intention. I have full respect for the coach and his authority."