The 50-year-old trainer believes that Massimiliano Allegri's men were fortunate to emerge from the clash with a point in their encounter at San Siro
Michael Ciani restored parity for the visitors with 18 minutes remaining to cancel out Kaka's stunning effort earlier in the second half but, despite bagging a point at San Siro, Petkovic admits he is unsatisfied at the result.
"We deserved to win at the end," the 50-year-old told reporters.
"I am not satisfied, as we need to face games with more determination. We allowed Milan the initiative in the first half, but the second was the complete opposite.
"Milan have a lot of quality and when they are able to play to their strengths any team will struggle against them.
"After the equaliser we improved and should’ve finished the evening with a victory. We lack that extra 10 per cent of determination away from home to win."
Petkovic's men, who ascended to seventh in the Serie A standings following the result, host Genoa at the Stadio Olimpico on Sunday.