The Brazilian pulled up inside 20 minutes and tried to play on before being replaced by Sergio Aguero soon after.
But the City boss had better news on Kevin De Bruyne, who was stretchered off during added time after going down under a heavy challenge from Jason Puncheon.
Guardiola says the Belgian’s injury isn’t as bad as perhaps was initially feared but admits he is unlikely to play against Watford in two days’ time.
“Hopefully he [Gabriel Jesus] will be one month, maybe two months he will be out," he said. "With Kevin we have been lucky in the past with what has happened from the same actions. I don’t know what will happen in the future.
“He may not be ready for Watford in a few days.”
Guardiola added that he wants to see players better protected by referees.
"Please, referees, they have to protect players," he said. "We were lucky against Tottenham and against Newcastle. Today we were not lucky.
"Referees have to protect. We know how strong physically it is England but teams miss big players, not just Manchester City. The replay speaks for itself. We have to protect players."
We will bring you more information on Gabriel and Kevin as we get it right here on mancity.com in the coming days.
Meanwhile, Guardiola says his focus now is on breaking our own record for consecutive Premier League wins.
The draw with Palace brought to an end our 18-match winning run, one short of equalling the best sequence in top-flight European history, currently held by Pep's Bayern Munich side.
It’s a staggering run that has seen City establish a 14-point lead going into the new year – and Guardiola wants to see it bettered in 2018.
"We set a record in Premier League but next one we will try to beat," he said. "We are in December, there are lots of games to play.”