Fernandinho's 90th-minute own goal ensured the Eagles claimed a draw at Etihad Stadium in a remarkable conclusion to the game.
Gabriel was a constant threat to the Palace backline but admitted the disappointment with only coming away with a point.
"We worked so hard in the last 25 minutes so we can score two goals and win the game," he said. "But the reality is different. We have to keep focused because the game was not over.
"Nobody is happy in the dressing room because we know we created more chances. We know we played so good. Now, we have to focus and work a little bit more."