Defoe has scored eight goals in cup competitions this season, but has found Premier League opportunities hard to come by, starting just one match.
Toronto manager Ryan Nelsen - who played with Defoe at Tottenham - this week admitted he would jump at the chance to take the 31-year-old front man, who has 18 months remaining on his contract, to MLS.
Villas-Boas insists the former West Ham man still has a big part to play for Tottenham as he strives to secure a place in England’s squad for next year’s World Cup.
"I have seen in the press that there is reported interest [from Toronto], but we want the player to stay on and hold on to those last years of his contract," the Spurs boss told reporters. "In the end the player is committed to the club and the club is committed to the player. The player at the moment is our top goalscorer and he is chasing the European record for the club as well which is important for his individual motivation.
"I think he is extremely happy, not only because of what he has achieved, but also because of the smile on his face. He has had a better start than he had last year. That is an impressive goals tally and he is a player that everyone cherishes."