Louis van Gaal had targeted the Senegalese winger to bring additional pace and directness to the United attack, and officials were sent to broker a deal with their Southampton counterparts this week.
However, they have been told that Mane will not be leaving St Mary’s in this current transfer window.
The player himself is relaxed about the situation, although he would jump at the opportunity of playing at Old Trafford if given the chance to do so.
The Senegal international also knows that he will have multiple options in the summer, after the 23-year-old told the club that he did not want to discuss a new contract.
These developments come after Mane was dropped for the loss against Norwich City at the weekend and publicly criticised by manager Ronald Koeman for missing a team meeting ahead of the fixture.
But Saints officials are confident that the whole incident was just a misunderstanding, as the Dutchman had brought forward the team meeting by ten minutes.
Southampton will listen to offers for Mane in the summer, such as his reluctance to commit his future to the Saints.