Dembele has been sounded out by LaLiga giant Barca as a replacement for Neymar, after his astounding $A331 million world-record switch to Paris Saint-Germain.
Speculation mounted that the France forward was Camp Nou bound after he missed training without permission on Friday (AEST).
Dortmund confirmed a bid for the 20-year-old from Barca had been rejected and that a transfer did not seem likely, before announcing the forward would be suspended for its DFB-Pokal clash against Rielasingen-Arlen on Sunday.
Peter Bosz's men won that game 4-0 but will not welcome Dembele back into the fold for their Bundesliga opener against Wolfsburg next weekend.
"Borussia Dortmund has decided to continue the suspension of the player Ousmane Dembele from first-team training until further notice," a club statement read.
Sporting director Michael Zorc added: "Our focus is now concentrated on the preparation of the for the opening Bundesliga match against Wolfsburg next weekend.
"Ousmane Dembele, of course, has the opportunity to train individually."