The Uruguayan also slammed the media for treating his South American compatriots differently to native players.
He said: 'When someone comes and says to me something bad about being a South American, I don't cry, because that happens inside the pitch.
'I have my conscience clean. But as I have said: Manchester United controls the media, they are powerful and the media will always help them.
'It's complicated to play here in England. As Carlitos (Tevez) and Kun (Aguero) has said, it's complicated for a South American footballer to be here as we are treated differently to the local footballers.
'But they have their culture, they are like this, you know. I have to play football, which is what I always wanted, but I have suffered a lot for being a footballer.