"We dropped two points and deserved to win this game against Milan," Martino told Sky Sport Italia.
"We created more scoring opportunities and that is why we would've deserved the victory. We made a mistake leaving the initiative to the Rossoneri when Milan scored their goal. We paid for that error.
"Lionel Messi played well, as did the rest of the team. He was in the thick of the action. It is not easy to play with so many opponents in their own half. We had the chances to score and it's just a shame we didn't make the most of them."
The draw keeps Barca at the top of Group H.