And they have approached Atletico themselves to see if they can get a deal done instead of United.
The Catalan giants have been forced to explore secondary targets after David Luiz agreed to move to Paris Saint Germain. They want to strengthen their centre-back position following Carles Puyol's retirement.
And Miranda, who was a rock at the back as Atletico won the La Liga title and reached the Champions League final, has emerged as their latest target.
Barca have reportedly opened discussions with Miranda's agent regarding a possible contract offer, while they're willing to offer Atletico €30m to persuade them to part with his services.
Reports in Spanish newspaper AS claimed that United had all but agreed the transfer of Miranda to Old Trafford. United need defensive reinforcements of their own, after the confirmed departures of Rio Ferdinand and Nemanja Vidic.
Atletico are thought to be lining up a move for Porto defender Eliaquim Mangala to replace the Brazil-born Miranda.