The manager told Sky Sports News: "We're in this sport and you're going to get injuries from time to time, but obviously it's a hugely disappointing one for Andros because I'm sure that he would have been on that plane to go to Brazil in Roy [Hodgson]'s squad because he is largely the reason why all the rest of the players are going there.
"He's single-minded and I'm sure that he's so strong in his mind that he's going to get over this setback and come back strong again. There's plenty more World Cups for Andros Townsend.
"This is a major setback for Andros and he's bitterly disappointed but he has nothing to worry about. He's played a huge part in getting the other 20-odd players on that plane and Roy himself. Andros knows that and he'll take that as a positive. On a negative side, he's got to wait another four years for a World Cup."
The 22-year-old scored on his international debut during the qualifiers, helping England to wins over Montenegro and Poland.