The World Cup finalists staged a bold attacking display in the first-half to go to the locker room with a three-goal lead in their Euro 2008 qualifier on Saturday.
After the break, Les Bleus looked satisfied with the result as they didn't stretch the score line.
"We could have been better, be more effective and score more goals in the second-half," Domenech was quoted as saying by the website of the French Football Association.
"Even in the first period, there were moments of distraction (when we could have conceded a goal) but William Gallas exceptional tackle saved us."
Domenech, though, said he was surprised by the players' mental strength in this stage of the season.
France will host Italy on Wednesday in the second game of Group B of the qualifiers.