Puig enjoyed a lot of game-time after the restart in June, indicating that he could in the club's plans heading into the 2020/2021 season.
However, Koeman has now revealed that he told the 21-year-old he won't get regular minutes this season and he should go out on loan along with Carles Alena.
"It is not true that I do not have him. I spoke with him yesterday before training. I am clear that young people have to play and I told him so," he said, as per Barcablaugranes.
"He, Aleñà, Pedri ... Young people like Riqui have to participate and I told him that it will be very difficult here because he will have a lot of competition. We are thinking about the best way to succeed at Barca.
"I have told him that he has a future here, but it depends on the player.
"I would recommend that he go on loan. Guys in their 20s like him have to play and cannot stand. We have drawn conclusions in these three weeks and Riqui has too much competition."
While Ivan Rakitic is the only senior midfielder to have been sold so far, Arturo Vidal is reportedly also on his way out as the club officially unveiled midfielder Mirlam Pjanic this week.