The New Zealander was considered a potential option for Louis van Gaal, as he looks to strengthen his backline in the new year, but it seems that the Dutchman has moved on to new targets.
United have been linked with the likes of Atletico Madrid's Diego Godin and Borussia Dortmund's Mats Hummels in recent weeks, and their attention has now seemingly been diverted away from Reid.
The Hammers centre-back is a key player at the Boleyn Ground, but his future remains up in the air because of his contract situation.
Reid's current deal expires in the summer, meaning that a number of Premier League clubs have been alerted to his potential availability.
The hope is that Reid will be purchasable at a cut price, due to West Ham's reluctance to lose him on a free transfer.
If United have dropped out, the Hammers will have one fewer team to fight off their prized asset, but that is no guarantee of his stay at the London club.
Arsenal and Liverpool are still reportedly interested and they are both expected to make offers during the next transfer window.
West Ham, meanwhile, are still hoping to tie the defender down for a long-term stay and discussions continue over a new, improved contract.