Stephan Lichtsteiner, Giorgio Chiellini and Arturo Vidal were on the scoresheet for the Serie A leaders at Juventus Stadium.
Like Rolando's second-half effort for Inter, Chiellini and Vidal scored scrappy goals, with the former coming after the visitors failed to clear their lines.
Mazzarri, who was particularly critical of midfielder Mateo Kovacic, said his team failed to match Juve's determination and aggression.
"I was annoyed at the way we conceded the second goal, as we had the opportunities to clear it and were too sluggish. Juventus were quicker to the ball, more aggressive and that made the difference," the 52-year-old coach told Sky Sport Italia.
"We need to focus on every little detail with great determination, the way Juventus do. When the going gets tough, they get going. Juve were more determined and aggressive, whereas we were sluggish and lazy.
"We created chances and let's not forget Rodrigo Palacio twice could've made it 3-2 to end with a siege on their goal."
Andrea Pirlo was particularly creative for Juve, completing 64 passes – including 22 in the attacking third and assisting Lichtsteiner's opener.
And Mazzarri blamed Kovacic for allowing Pirlo to dominate, with Ruben Botta praised for his efforts after coming on for the Croatia international in the 66th minute.
"This game was very simple tactically, as there were duels all over the pitch. In those situations the players most accustomed to being at the top and to winning will win the duels," Mazzarri said.
"I saw the possession almost equal, so it wasn't dominated by Juventus, but the details do make the difference in these games.
"I thought Kovacic was in the ideal position to play brilliantly, as he'd have more space when going deeper. We knew he had quality.
"After Ruben Botta came in, Pirlo wasn't quite so free. There was meant to be someone on him – Kovacic – and that person didn't go enough, so he'd get stuck in between and leave us a man down in midfield."
