Mazzarri was also keen to praise his opponents, who will now defend the lead in Prague after the win in Italy.
"We will do our best to go through," Gazzetta dello Sport quotes Mazzarri as saying.
"We want to undo the damage that was done in the first leg. My players want to put in the effort it will require. We will do all we can for 95 minutes.
"In the first game we were not good but I must also compliment Viktoria because they are a very good team."
Napoli are currently four points behind Juventus in Serie A.