United have been continually linked with a move for Bale and reports suggest Moyes could give the green light for United to launch a bid for the Welshman.
Bale's future at White Hart Lane is again set to be the subject of intense speculation this summer after another stellar campaign for Spurs with all the top clubs in Europe credited with an interest in the attacker.
However, Villas-Boas is keen to ward off any interest in Bale by tying down the player to a new deal and thinks even Manchester United could not afford to sign the 23-year-old this summer.
"I'm pretty sure that whatever David does in the market will be excellent. But to get a player of Gareth's dimension is firstly not in our interests but also very, very difficult to get," insisted Villas-Boas.