The Norway striker did not come off the bench as City beat the MLS side 2-1 on Wednesday night.
Guardiola has now revealed the £51million signing has been carrying some fitness problems since arriving at the Etihad.
However, Haaland is expected to feature against Bayern Munich in their next match.
Guardiola said: “Next game, Erling will be ready. He’s had niggles and a few problems. We’ll see.
“He’s trained just two sessions and didn’t want to take risks. The season is so long.”