Inter saw their seven-game league winning run in come to an end at the league leaders, with Juan Cuadrado's stunning 45th-minute strike deciding the match.
However, Pioli spotted two incidents before Cuadrado's goal that he felt should have been picked up on by Rizzoli, who later sent off Ivan Perisic for dissent.
"There were two penalties for us - one with [Giorgio] Chiellini on [Mauro] Icardi and another incident with [Mario] Mandzukic," he told Mediaset Premium.
"We created opportunities but the decisions did not go in our favour. The images I have seen are clear, and we've paid dearly for these errors.
"The performance was good against the strongest team [in Italy]. We are approaching their level as a team.
"Our disappointment is for our mistake [on the goal]. We left an important area for Cuadrado."