Zola made six changes to the team that won 3-0 at Nottingham Forest on Saturday, including benching 30-goal strike duo Matej Vydra and Troy Deeney.
The Hornets failed to find the net for the first time in 14 league games and missed the chance to move up to second in the table, but the Italian defended his team selection.
"No I don't regret that," he said. "We have a lot of games to play and this is a team, it is not just about the first 11.
"We have other players who have been very good for this club and this team when they play. They are all going to be important.
"Losing is part of the game. You win and do well like we have been recently and then you play a bad game like this.
"We are not a team who are going to be invincible and will win all the games.
"We were in a good spot and we are going to keep pushing. We know that we need to improve on this, we made some mistakes and we didn't expect them to play in that way.
"That and the lack of quality in the last third has caused the problem.
"I think what is important is the reaction. Saturday we have a big game and I am expecting a good reaction from the players."