Van der Vaart has been an undoubted success since he signed from Real Madrid two years ago, but the Dutchman had to settle for a place on the bench last week at Newcastle, with Villas-Boas selecting Gylfi Sigurdsson for his first game in charge.
The Dutchman has been strongly linked with a return to former club Hamburg. Villas-Boas refused to guarantee that Van der Vaart would be at Spurs when the transfer window closes, but when asked whether it was his intention to sell him, the Portuguese said: "No, on the contrary. He's a player of great importance for us, a player I count on."
He continued: "I'm not sure if Hamburg are interested but he's a player who at the moment is not for sale. Anything can happen but he's a player we are counting on."
Spurs put great effort into landing Sigurdsson this summer amid strong interest from Liverpool. Villas-Boas seems to have a lot of faith in the former Hoffenheim player, but denied that Van der Vaart is no longer in his first-team plans.
"Rafa was very unlucky because when he came from his vacation after the Euros he got injured in the game against LA Galaxy so he missed most of our pre-season in America and Sigurdsson was with us all pre-season," Villas-Boas said.
"He couldn't therefore play against Watford and Valencia so he came back late for selection and it was pretty straightforward to select Sigurdsson for the Newcastle game. Now Rafa has trained with us all week and he's looking strong and in contention."
As well as Van der Vaart, another player who has been linked with a move from White Hart Lane this week, Michael Dawson, is also in contention for Saturday's game at West Brom. Dawson, who has been at the club since 2005, was surprisingly allowed to talk to QPR this week after Spurs accepted an offer from the west London club.
That deal appears to be on the verge of collapse, although other interested parties such as Sunderland and Stoke could still make a move for the England defender. Villas-Boas is not desperate to lose his club captain, but insists he still has enough capable players in reserve should Dawson depart.
Villas-Boas said. "We have four good players, it's already enough. We have Steven Caulker, who went through a fantastic Olympics and has gone into the national team in England, we have William Gallas, an experienced central defender with Premier League titles and World Cup titles, Younes Kaboul is a French international and Jan Vertonghen is a Belgian international."