The loss at the Scotstoun Stadium was the Warriors' second from their opening two games of the competition, leaving them bottom of Pool 4.
"We have got four games to play and we'll have to win all four to qualify. I believe we have got a group of players who are capable of doing that," Townsend told Sky Sports News.
"By the time the games come around in December we should have a bigger squad with the players coming back from injury."
Glasgow return to European action on December 7 when they entertain French side Castres.