The Eastlands club made a £38million bid for the 21-year-old and met his buyout clause at Benfica.
A source in Lisbon told News of the World: “City offered the amount required to trigger a release clause in Di Maria’s contract but the boy is loyal to Benfica.
“But everyone at Benfica accepts that he will move on sooner rather than later.”
Di Maria, who has been linked with Chelsea, Manchester United and Inter Milan, signed a new deal with benfica last October that will keep him at the club until 2015.
