The centre-back has been hotly tipped with a move to Queens Park Rangers in recent days, and Spurs' potential loss of a recognised Premier League defender has been criticised by some.
However, Villas-Boas has insisted that there are plenty of centre-backs at the club good enough for the league.
"I don't think it's a gamble," PA Sport quotes Villas-Boas as saying. "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."
Dawson has made 167 league starts for Spurs since signing from Nottingham Forest for £4m in 2005.