Kepa was dropped as a consequence of his behaviour during Sunday's Carabao Cup final when he defied Sarri's orders and refused to be substituted. He later apologised and was fined by the club, while the manager declared the situation to be over.
"It's a choice. It's a message for my group. We are a group - not 25 players. It is my choice," Sarri told BT Sport in a post-match interview.
"I think it was the right decision, Kepa made a big mistake, he paid with the club, and then he had to pay with the team," he said in further quotes published by Sky Sports.
"But now I have to think we have to stop, Kepa from tomorrow will be with us. He is back in the team for the weekend, I don't know in the next match if he will be on the pitch or not, but one of the next two he will [start]," the boss added.
Meanwhile, on the subject of his own potentially precarious position after a difficult few months in his debut season, the Italian coach has insisted the media has blown things out of proportion.
"It depends more on [the media] than the club. I spoke with the club two or three times in the last few days. The problem wasn't so big as you wrote. Maybe it wasn't the truth, I don't know, but it's not a big problem for me," he said at his post-match press conference, via ChelseaFC.com.
"In this job you are under pressure, if you are lucky, every six months. It's normal if you lose two matches in a row you are under pressure, maybe more [pressure] at Chelsea."