Dodi Lukebakio struck both goals for the visitors on the night.
Gonzalez said afterwards, "The team has started the match well, pressing well, except in the action of 0-1. That has tilted the match.
"Lukébakio's talent is what has made the difference. We have had chances and we have not been able to score. We are annoyed, but we have to keep working."
On the fans' anger at the final whistle, Gonzalez added: "I think the result is not fair, but it is normal for people to leave angry, their team has not won. It is legitimate and normal. I am not fooling anyone, it will be a very difficult and very hard season. We need them and that is how it will be.
"Today we did not compete badly, but their mistakes or successes have condemned us. Now we have to lift our heads and get points. We knew it would be a tough year."