The Argentine defender was unimpressed with his side's start in the Derby della Madonnina, while Samir Handanovic feels the Nerazzurri must improve
The Nerazzurri fell 1-0 down before the break when Stephan El Shaarawy opened the scoring, but they eventually recorded a draw following Ezequiel Schelotto's equaliser in the 71st minute.
"It was a very intense derby. Milan were better than us in the first period but Inter pulled out all the stops to get the equaliser," Zanetti told reporters.
"It's all to play for now. I'm especially pleased with how we did in the second half and how we approached the game."
Meanwhile, Inter goalkeeper Samir Handanovic, who impressed with a string of fine saves, stressed that the Nerazzurri still have work to do, while voicing his delight with his save from a Mario Balotelli chance.
"I don't think we got our approach wrong at the start. Perhaps at a certain point a little bit of fear started to set in. We need to improve, we realise we're not finding everything plain sailing, there's still work to be done.
"All saves are difficult, you can't say some are more difficult than others. The save I was most pleased with? The one when I dived low at Balotelli's feet."
Inter currently sit fourth in Serie A with 44 points from 26 games.