The 20-year-old is one of La Liga's top talents and has attracted interest from overseas following a series of fine performances during the Mestalla-based side's eye-catching start to the season.
Jose Mourinho is thought to a a big fan of the creative central midfielder as he looks to reduce his side's reliance on Paul Pogba.
Soler made his first team breakthrough last season and has been a key member of the 'Los Ches' side this season, starting every league game.
Valencia acted quicky in the face of the interest in the youngster, tying him down to a long-term contract with a £71m release clause.
However, United remain keen on the player and are plotting a £45m bid when the transfer window reopens in January.
According to English publication 'The Sun', the player has begged his current employers to negotiate with United, who could opt to use Andreas Pereira, who is currently on loan at Valencia, in part-exchange.
Speaking to 'Cadena COPE' recently, Solder refused to talk about his long-term future, saying: “You already know it, I’m focused on Valencia.
“Regarding those things (the interested from Manchester United) I know nothing.
“It would be foolish to think about those things right now.”