Wenger left out eight first-teamers in the Czech capital and admitted: "The young players found that playing away in the Champions League is not so easy and they will do better in the next games.
"Defensively we did well but our offensive performance was only average tonight. Our tempo was not high enough to create space or chances.
"The conditions made it very difficult and Slavia were determined not to concede after we humiliated them 7-0 at the Emirates a couple of weeks ago.
"But overall the result is quite positive because we came here to qualify and we have done that with two games to go and without conceding a goal.
"We know we can play better than we did tonight but it is still an outstanding achievement to be through to the next round after only four games.
"Now it is important to make sure we win this group and give ourselves an advantage in the draw for the second round of this tournament.
"But I will continue to rest and rotate my players in our next two games and there is a good chance the youngsters will play again in our next game in Seville."