Olivier Giroud scored the only goal in the first half to hand Arsene Wenger's side the north London bragging rights and condemn Spurs to their first defeat of the season.
Townsend believes that Tottenham dominated after the break, which he found encouraging after failing to score from open play thus far this term, but was unhappy to lose such a high-profile game.
|21/2||Spurs are 21/2 with BetVictor to beat Norwich City 3-0
"There were positive signs - we dominated the second half - but the result is the main thing and we couldn't find the back of the net.
"We came to the Emirates Stadium and took the game to Arsenal. We did everything but score and got undone on the counterattack. That's how it goes sometimes."
Townsend was called up by Roy Hodgson to the England senior setup for the World Cup qualifying double-header against Moldova and Ukraine and the midfielder hopes to return to White Hart Lane refreshed.
"We've got the international break now but we'll all come back from that, work hard and move on quickly from this," he vowed.