The Argentina international, 29, signed a new contract last year that runs to 2021 but the Toffees are hopeful of concluding a deal.
Harry Maguire’s arrival at Old Trafford means United manager Ole Gunnar Solskjaer has seven central defenders in his squad.
Everton inquired about England defender Chris Smalling on Wednesday but that interest was rebuffed.
Meanwhile, United have ended talks over signing Juventus’ veteran striker Mario Mandzukic.
United were considering an offer for the Croatia international as they look to plug the gap created by Romelu Lukaku’s impending £74m exit for Inter Milan but have decided the financial demands were excessive for a 33-year-old.