The Nerazzurri came from behind to lead 3-2 but quickly threw away their advantage, and Zanetti admits that his team are failing to take their chances.
"We need to manage periods like this and figure out our mistakes," he told Inter Channel. "That's how you become a great team.
"We're not able to make this step up in quality which will allow us to stay up at the top of the table, where we want to be.
"We're definitely angry and full of regret. We had chances, we were able to turn things around but then sadly they drew level."
Inter are currently fourth in the Serie A table.