Napoli coughed up a 1-0 lead to drop two points against Toro.
"Compliments to Torino for causing us problems," Mazzarri told Sky Sport Italia.
"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 naïve to concede that equaliser so late. We have to improve before we can compete with the top teams."