The La Liga champions narrowly missed out on luring the Spain international to the Bernabeu in August 2015 but will resume their pursuit of the stopper as early as next week.
Failure to register the signing of De Gea prior to the Spanish transfer window closing two years ago saw the 'keeper remain at Old Trafford where he has been one of the club's star performers since arriving from Atletico Madrid in 2011.
Yet Real's interest in the 26-year-old has not relented and they will begin attempts to bring him to the Spanish capital in the coming days in an effort to avoid a repeat of his failed move to Madrid.
Manager Zinedine Zidane has been keen for nothing to distract Real from attempts to win a record 12th European Cup.
Keylor Navas will start in goal for the game in Cardiff, yet his position as Real's number one heading into next season will be in serious jeopardy should De Gea swap United for a return to his homeland.
The Daily Mail understands that United will demand a world record £70m from Real to sign De Gea. Manchester City's £35m capture of Ederson - breaking a 16-year record fee for a goalkeeper - has ratcheted up De Gea's market value and United will look to take advantage should he indicate a desire to leave.
De Gea has developed into one of the Premier League's leading custodians during his six years in English football; being named in the PFA team of the season in each of the last five campaigns. However, in the wake of Zlatan Ibrahimovic and Paul Pogba's arrival at Old Trafford the player is frustrated at the club's failure to challenge for the title.
But De Gea is in no rush to leave United like he was during Louis van Gaal's spell at the club and is understood to be "content" with life under Jose Mourinho. He is contracted to the club until 2019 and with the option of a 12-month extension the 20-time English league champions are under no pressure to sell.
Cristiano Ronaldo meanwhile has quashed the renewed speculation regarding De Gea in an attempt to back Navas ahead of the final. The Ballon d'Or holder, who spent six years at United between 2003 and 2009, told The Sun: "Keylor Navas is Real Madrid's goalkeeper. De Gea is a very good keeper but he is at United. They talk about 50,000 footballers every year and they are always the same. Of the players they talk about, maybe one or two will arrive and that's it."