Gabriel turned 16 this week after asking United to cancel his registration last month, triggering concern at the club over the future of one of their most highly rated academy prospects.
The Guardian reports that United have now submitted a scholarship offer covering next season. Under Premier League youth rules, the club needed to make that offer to prevent Gabriel from leaving for a rival without a negotiated fee in January.
However, the offer does not guarantee he will remain at Old Trafford. Relations between the club and his representatives have deteriorated following a disagreement over the pathway to first-team football.
Gabriel is believed to be unlikely to accept the offer, with his future still unresolved.
If he moves to another Premier League club, United would have to negotiate a fee directly with the buying side. Should the clubs fail to agree, compensation would be determined by a Professional Football Compensation Committee tribunal.
Manchester United would expect a tribunal to award more than £3 million, alongside a clause entitling them to 20 per cent of a future transfer fee.
The club could receive substantially less if Gabriel moves abroad. Official FIFA compensation figures for a Category I academy suggest United would be entitled to around £350,000 in that scenario.
Gabriel's eligibility for an EU passport through his parents means he could move to a European club before turning 18, despite the restrictions that normally apply to international transfers involving minors.
Real Madrid are reportedly favourites to sign him, while Barcelona, Bayern Munich and Paris Saint-Germain are also monitoring developments.
Gabriel has been at United since the age of 11 and has not attended training for more than three weeks, according to the report. Sources say the club have made several attempts to check on his wellbeing.
United had invested in his development, with specialist staff usually reserved for senior players helping to accelerate his progress towards the first team.
A team photograph released this week briefly raised hopes among supporters that the situation might be improving. However, the disagreement over his future remains unresolved.
Gabriel was permitted to sign a pre-agreement after his 16th birthday, but his representatives were not prepared to enter discussions following the dispute over first-team opportunities.
United's scholarship offer gives the club a formal step towards protecting its position, but it may not be enough to keep the forward. His next move remains undecided, with several leading European clubs watching closely.