Barcelona have been warned by Ajax sporting director Marc Overmars that Frenkie de Jong is not for sale this summer, but a deal next year is possible.
De Jong, 21, has drawn interest from Barca, and Mundo Deportivo claimed this week that the Spanish champions will push to sign the midfielder during the current transfer window.
However, Ajax, who have already sold Justin Kluivert to Roma this summer, say they will stand firm in keeping their remaining assets at the club.
"Frenkie de Jong, Donny van de Beek and Matthijs de Ligt are not for sale if it is up to us," Overmars told De Telegraaf. "Let them play 40 games in a season for Ajax first."
"[De Jong is] not for sale. I have communicated that to all the different parties."
Overmars also said that Matthijs de Ligt and Donny van de Beek will also be staying at the Johan Cruyff Arena for now.
Eighteen-year-old central-defender De Ligt has been linked with Barca, too, as well as Tottenham, Manchester City and Bayern Munich.
Young midfielder Van de Beek has also been the subject of transfer speculation but Overmans told the interested clubs to wait until next summer.
"They can come back next year," he said. "Of course, the deal for Davinson Sanchez [who moved to Tottenham last year] proved it's difficult for a club to stick to their word. But we are at a point where we say: 'Guys, we don't sell, they are 19, 20 years old.'
"To players and agents, I say that a transfer after this season for the right price is worth a conversation -- and we talk about that with interested parties."
Barcelona have already signed midfielder Arthur Melo from Gremio, as well as Sevilla defender Clement Lenglet, but sources close to the club have confirmed to ESPN FC they are still targeting another midfield player.