The 16-year-old's family fell out with the Ligue 1 club earlier this summer after they attempted to annul Mejbri's contract, which expires in 2021.
However, the impasse is set to end this week as United close in on a £9m deal, half of which will be paid to Monaco up front.
Paul Pogba and Anthony Martial were reportedly instrumental in persuading Mejbri to move to Old Trafford.
The talented midfielder is the son of Lotfi Mejbri, a former Tunisia international.
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.