Moutinho was expected to be the focus of their attention on deadline day, but Tottenham appear unlikely to sign the 25-year-old due to a 40million euro (£31.7million) release clause in his contract.
"It's an impossible deal for the club," Villas-Boas told a press conference.
"You have to bear in mind that this is a player with a 40million euro release clause.
"This volume of money is out of Tottenham's possibility.
"Bearing in mind that this is a key player for club and country, you wouldn't say that you would get him at half the price and half the price is already bigger than Tottenham's record fee."