The Catalan club were heavily interested in securing the services of the 21-year-old over the summer, having seen Atletico Madrid superstar Antoine Griezmann snub a move to Camp Nou.
"Maybe someday I'll join Barcelona, but not this season," he told NOS. "I'm staying at Ajax. I think it will be a good year."
And Overmars is insistent that, even if Barca were to return with an improved offer, Ajax will keep one of their most talented youngsters.
"Barcelona can return in January if they want, but no player will leave," he is quoted as saying by AS.
Overmars, the former Arsenal forward, also claimed that Barca's offers were "unfortunate" and that they did not "value De Jong".
Reports also claim that Tottenham made a bigger offer for De Jong, though those overtures were also rejected.
De Jong's stock has continued to rise in the Netherlands, and he has won two caps for his country, and is closing in on a half-century of appearances for the capital club.
A versatile player, he can fill in at centre-back when required, though his preferred position is central midfield.