The Frenchman has been linked with a move to Old Trafford in the past and the Red Devils were eyeing up another bid for Dembele in the coming weeks.
But an injury sustained by the 24-year-old at the European Championships with Les Blues has ended any hopes of a Premier League transfer.
Spanish publication Sport claim that United were prepared to pay €50million (£43m) to secure the services of Dembele, but will now have to reconsider their options.
Dembele was forced to withdraw from France’s Euro 2020 squad after picking up a knee injury in their second group stage game against Hungary, and Barcelona have since confirmed he has successfully undergone surgery.
The La Liga giants added that he is now likely to miss four months of football, in what will come as a hugely disappointing news to both Barcelona and the player himself.
Dembele has struggled with injuries ever since signing for Barcelona in 2017 and will now suffer the consequences of yet another cruel blow.
It is understood that United were close to recruiting the France international last summer, though he refused to leave the club he signed for in a £135.5m deal four years ago.
Barcelona had hoped to recoup some of the money they spent to sign the talented attacker, though Ronald Koeman’s side could now be forced to lose Dembele for free unless a new deal is agreed.
The former Borussia Dortmund man is out of contract next summer and will become a free agent unless the Spanish club are able to tie him down to a new deal.
Ole Gunnar Solskjaer’s side may well recover from this situation rather promptly as the Red Devils close in on the signing of Jadon Sancho.
Sancho is currently on international duty with England at Euro 2020, though United have already agreed personal terms with the 21-year-old and are edging closer to capturing their main transfer target.
Dortmund and United were unable to agree on a transfer fee last September after weeks of transfer negotiations, but the two clubs have made progress with talks on this occasion.
The Bundesliga side were demanding in excess of £100m for Sancho in 2020 but have been forced to lower their asking price due to the financial complications caused by the coronavirus pandemic.