City rivals Inter, who are level on eight points with Milan, were thumped 4-1 by Cagliari at San Siro and Fiorentina also failed to win.
But Inzaghi's men could not steal a march as they were frustrated at newly-promoted Cesena.
Milan went behind after Christian Abbiati's mistake allowed Davide Succi to tap home after 10 minutes.
Adil Rami's towering header provided an equaliser soon after, but Milan could not force a winner and even had to play the final 17 minutes with 10 men after Cristian Zapata's red card.
Although Inzaghi feels his team is improving, he knows they missed a great chance to move away from teams around them in the league.
He told Sky Sport Italia: "Unfortunately we had the game in hand and created so much in the first half, but when you work so hard and don't score in this heat you will pay eventually.
"We played very well in the first half, then got stretched out and it was tough to win after going down to 10 men. We probably deserved to score a second.
"I cannot complain about the team's performance and their goalkeeper made some crucial saves, but we started to run out of steam when we didn’t make all that pressure count.
"It's a shame, as this weekend Inter lost and Fiorentina drew, so the teams we are jostling for position with all slowed down.
"As a coach I need to look at improving the team game by game and I feel we are doing that. We have a good team spirit and maybe those who watch us risk a heart attack, but at least they are entertained! That's what we wanted to bring back to Milan.
"We have to remember we were eighth last season, we are playing good football now and it will take time and hard work."
