The Spanish keeper has been a long-term target for Real, and according to the reports, they have already seen a £60m bid rejected by United this summer.
"I don't think they need David de Gea, but David de Gea is an upgrade on Keylor Navas," the former West Ham keeper said on ESPN FC.
"He started off this season with an injury and kind of stuttered especially early on.
"But you don't win back-to-back Champions Leagues, regardless of how good you are, how good the other 10 are, without having a quality goalkeeper between the sticks.
"But Real Madrid have no need to go out and buy a goalkeeper for buying a goalkeeper's sake."