Mazzarri's side had taken an early lead through Edinson Cavani, and while the coach congratulated Torino for their goal he was annoyed at his own side.
"Compliments to Torino for causing us problems," Sky Sport Italia quotes Mazzarri as saying.
"We are paying the price for such a packed fixture list, as we must improve and grow. We had the chances to close the result. The game was finished, so it's a shame we conceded.
"It was a difficult match, Torino played well and we were naive to concede that equaliser so late. We have to improve before we can compete with the top teams."
Napoli are third in Serie A, five points off Juventus at the top.