United were eager to sign the 18-year-old, who is one of the standout youngsters in world football.
Manchester United agreed a deal worth £133million for Ansu Fati with his agent Jorge Mendes
United attempted to bring in Fati for a significant fee despite their financial problems. They are on course to record losses of nearly £200million during the current campaign.
Fati has a release clause of £357million (€400million) in his contract.
Despite Mendes agreeing to the deal, Barcelona refused to sanction the sale of the prospect
Fati, one of the standout youngsters in world football, has a release clause of £357million
The starlet has already made 43 appearances for Barcelona, during which he has scored 13 goals and provided five assists.
In addition Fati has broken into the Spain senior squad and has been capped four times.
However, he is currently sidelined with a meniscus injury that could keep him out for four months.