Spurs are unwilling to sell the Wales winger at any price with Villas-Boas outlining the club's position at a press conference ahead of the Barclays Asia Trophy in Hong Kong.
"On Gareth I want to repeat what I was telling you last season and what I was telling you from the beginning of pre-season so I cannot extend myself," he said.
"He's a player that we are willing to continue to have, he's a Tottenham player, he's one of the most fantastic players in the world at the moment and we are counting on him for the future.
"Unfortunately against Sunderland (tomorrow) he won't be fit to play, he's recovering from a knock he had in training so we expect him hopefully to have some involvement in the second game."
Villas-Boas also announced that Danny Rose, who spent last season on loan at Sunderland, will be required at Tottenham when the new campaign begins.
"Danny has had an excellent season. He's one of the players that we all want for our future," Villas-Boas said.
"It was one of those occasions where it's all worked out extremely well for him and he will definitely be part of our squad this season.
"Credit to him for making it work. This year he'll want to be involved with Tottenham and hopefully he'll have a big future ahead of him."
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- Barclays Asia Trophy