Haaland is struggling for form - just like many of his City teammates - and Guardiola insists the striker isn't to blame for the team's crisis.
He said, "First of all, merry Christmas everyone. It's about us, it's not just about one playing. When Erling was so prolific, it was about us, the team. Erling is so important for us and will be so important for us. We need to use him better.
"The reason why is this one and this one and this one. It is about us, about everyone. The guys are running more than ever. Many little details and big details make us not as good as we were."
On facing Everton, Guardiola also said: "They are not the perfect opponent. It is about us to come back to our best. It will take time. We have to get results as quickly as possible. We are facing Everton and they are in a good moment, their results and performances show it.
"We train today and tomorrow night. We will stay over here and play on Boxing Day. Today will be at home with their family and then tomorrow morning. Hopefully, they'll want to be here tomorrow night because it is our duty."