The Valencia star, who can play on either wing or behind the strikers, has been linked with United since Cristiano Ronaldo's departure to Real Madrid last year.
Madrid have are also keen on the £22million-rated Spain international and hope to tempt his cash-strapped side this summer, despite Valencia's qualification for the Champions League.
White hot: Silva (right) tries to get the better of Deportivo La Coruna's David Rochela
'When you hear a club like Manchester United are interested in you it is an honour,' the 24-year-old told the Daily Express.
'I am very aware of the Premier League, and in recent years it has been the stand-out league in the world. If it came calling, especially if it was a club like Manchester United, it would be very hard to resist.
'I am happy at Valencia but every player has his price and if they get an offer they think is good business anything is possible.'
Rafa Benitez is also an admirer of the Euro 2008 winner, but failed in a bid to sign him for Liverpool last year.
Euro star: Silva (right) scores for Spain against Russia during the 2008 European Championship
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