Sky Sports reports how the 23-year-old has been the subject of intense transfer speculation in recent months, with suggestions that the Welshman could leave north London this summer.
A switch to Old Trafford has been mooted, with Sir Alex Ferguson recently admitting that Bale was "the one that got away" when he opted to join Spurs from Southampton in 2007.
But, Manchester United could reignite their interest if Moyes decides to launch a bid for the recently crowned PFA Player of the Year and Young Player of the Year when the transfer window reopens on July 1.
However, Villas-Boas is keen to ward off interest in Tottenham's star player, urging the club to secure Bale to a new long-term deal at White Hart Lane, adding that it will be near impossible for anyone to sign him this summer.
"I'm pretty sure that whatever David [Moyes] does in the market will be excellent," the Portuguese tactician told Sky Sports.
"But to get a player of Gareth's dimension is firstly not in our interests but also very, very difficult to get."