United turned their attention to Dembele in the closing stages of the window after failing to land Jadon Sancho from Borussia Dortmund.
The French winger reportedly came around to the idea of joining United following a conversation with Paul Pogba.
But ultimately, Dembele turned down the chance to make the move and as a result, Barcelona’s efforts to sign Memphis Depay from Lyon were scuppered.
According to ESPN, Barcelona were annoyed by Dembele’s decision as they made it clear that he would not be guaranteed regular playing time if he remained at Camp Nou.
The report claims that the winger’s decision to stay ‘did not sit well’ with Barca’s hierarchy.
United’s preference was to sign Dembele on loan for the season, however, Barcelona were keen to permanently offload the 23-year-old.
The Spanish club were even willing to take a hit on the initial €105 million (£96.8m) they paid to sign Dembele from Dortmund in August 2017.
Dembele, meanwhile, has been training on his own as he is intent on securing a regular role under Ronald Koeman.
Barcelona’s players had been given four days off over the international break but Spanish reports claim that the winger has opted to train as normal instead.
He was also close to being left out of Barca’s matchday squad for the win against Celta Vigo last week before he replaced the injured Junior Firpo.