Vidal has been a pivotal player for the Italian champions in recent seasons, scoring 40 goals in three campaigns, all of which have ended with the Turin club winning the Serie A title.
However, the Chile international has been consistently linked with a move away from the club in recent times, with UEFA Champions League holders Real thought to be keen on luring him to the Santiago Bernabeu.
United, now led by former Netherlands coach Louis van Gaal, are also rumoured as potential suitors of the 27-year-old.
The doubt over his future at Juve has increased following the departure of Antonio Conte, who left the club on Tuesday and was replaced by Massimiliano Allegri the following day.
Juve chief executive Giuseppe Marotta insisted Vidal was not for sale at Allegri's introductory press conference on Wednesday.
But Vidal has done little to quell rumours of his potential exit by staying coy on talk of a potential switch to Spain or England.
"It's difficult to speak of other teams when you are already at a top club," Vidal is quoted as saying by Chilean newspaper La Cuarta.
"I have won the Serie A title three times and I respect my team-mates.
"I have heard about the interest shown by Real Madrid and Manchester United in me but it is my agent who deals with this.
"Have I completed a cycle [at Juve]? I don't feel that way. Perhaps I will remain at Juventus all my life.
"Once I arrive to Italy I will speak to the coach and see what happens.
"Now the only thing on my mind on is that I have seven or eight days of holiday left and I want to go away from Chile in order to have a good rest."
