Beckham was upset by the agreement and has no plans to meet with Joan Laporta, who is running for president of the Barcelona club, said the player's management company, SFX.
The English and Spanish teams agreed on the transfer, but the deal was contingent on Laporta winning Sunday's election and Beckham agreeing to contract terms.
"David is very disappointed and surprised to learn of this statement and feels that he has been used as a political pawn in the Barcelona presidential elections," SFX said.
Laporta said he would be talking to Beckham as soon as the player returned from the United States. Beckham is recovering from a broken right wrist.
"If I am not elected president, I would turn over the transfer to the man who does win," Laporta said at a news conference.
Another candidate in Sunday's election, Josep Martinez-Rovira, said he had no interest in signing the England captain, perhaps the world's most recognizable soccer star.
"Beckham is a media signing and more of a dream than reality. He is a player we would never try to sign," Martinez-Rovira told Spanish radio.
He said Beckham passes well but does not score enough.
"Beckham makes a lot of news off the pitch, but we're not interested in appearing in gossip columns," he said.
Announcement of the transfer agreement came after months of speculation about his future.
Another Spanish club, Real Madrid, and the Italian teams AC Milan and Internazionale also had been linked to a possible move for the 28-year-old midfielder.
As is customary in transfers, no fee was disclosed by Manchester United. Newspaper reports have said any bid for Beckham would have to be at least $48 million.
Beckham has helped Manchester United win six of its eight league titles in 11 years and the European Champions Cup in 1999. He has been at Manchester United for almost 13 years, including its youth teams.
Beckham is in Los Angeles with pop star wife Victoria, formerly of the Spice Girls. Before Tuesday's announcement, he had told the Los Angeles Times he was happy to stay at Manchester United but had never said he would remain there for the rest of his career.
Beckham is paid a reported $143,000 a week at Manchester United. He is worth $79.5 million, according to a recent survey of Britain's richest people in "The Sunday Times." He has a myriad of endorsement and sponsorship deals and is featured on billboard and magazine covers around much of the world.
If the deal does go through, Beckham could face his old team for the first time Aug. 3. Manchester United plays Barcelona in an exhibition game that opens Philadelphia's new Lincoln Financial Field.
Manchester United's U.S. tour is aimed at enhancing the club's profile in a country where soccer takes a back seat to other sports.
Beckham is getting even more visibility of late in the British film "Bend it Like Beckham," with the title based on his trademark ability to curl a free kick over a wall of defenders into the net.
Although Manchester United is soccer's wealthiest club, making big profits every year, it cannot afford to buy players without trying to balance the books.
Two players the club is said to be interested in are Brazilian World Cup star Ronaldinho of Paris Saint Germain and Harry Kewell, Leeds United's Australian forward.
"There will always be changes at a team like Man United," Beckham has said.
Beckham has dismissed suggestions of a rift with Manchester United manager Alex Ferguson despite several publicized fallouts.
Ferguson left his star player on the bench several times last season. In the locker room after a 2-0 loss to Arsenal, Ferguson kicked a soccer shoe that accidentally struck Beckham above the left eye.
"Despite what many people say about me and Sir Alex Ferguson, he's been a father figure to me," Beckham said.
By Robert Millward