Barcelona were informed last month that they would have to raise £178million from selling current players if they are to have any chance of enter the market.
Club president Joan Laporta had previously claimed the club was in a strong position and vowed no player sales would be necessary, but vowed to cut £150m from the wage bill.
According to the Barcelona based newspaper Sport, the club will prioritise the sale of fringe squad members but could approve sales of more established names should it be required.
De Jong was reportedly one of only three players who ‘will not be sold under any circumstances’ by the club.
Defender Ronald Araujo and midfield star Pedri are also considered untouchable by Barcelona, it is claimed.
De Jong’s status is a blow to Manchester United, with Erik ten Hag having been a long-standing admirer of the Dutch midfielder since he coached him at Ajax.
Ten Hag had been keen to sign the central midfielder last summer, but the midfielder opted to stay at the Nou Camp.
The midfielder has been central to Barcelona’s title challenge in La Liga, with the Catalans holding a 12-point lead over rivals Real Madrid heading into the closing weeks of the season.