The Argentine struck late on to give Roberto Mancini's side a 1-0 win in their FA Cup final dress rehearsal at the Etihad Stadium.
But the Spaniard felt his Latics side deserved a lot more from the clash with both Franco Di Santo and Arouna Kone missing good opportunities for the visitors.
He told Sky Sports: "Obviously in this moment of the season the points are vitally important otherwise I would tell you it doesn't matter.
"The way we performed was outstanding. I don't think for one second we deserved to draw the game, never mind lose it.
"I thought we were very sharp, we had good opportunities to score a goal and if anything you have to take those chances.
"I don't think there are many teams that can come here and limit Manchester City to two shots on target and I do feel we were very unfortunate today because our performance was magnificent, as good as it gets when you come here.
"We haven't scored and that's hard to explain. I think the three or four of the chances were really open and probably that was the difference. I couldn't be prouder."
The Latics still have a game in hand over the teams directly above them and now face West Ham away at the weekend before a testing home clash against Tottenham.
"Overall, it is three points lost and that's something we have to get over and prepare for Saturday," he added.