Gabriel now has 13 goals this season but Guardiola – who kept first-choice striker Sergio Aguero on the bench – demanded more from the 22-year-old.
“He's a young player, but the way he defended and fought was good," said Guardiola.
“He has to improve and he knows that, but every day he gets better and better.
“What he's shown so far in the period he's here, he's had ups and downs with his age and with injuries, but he's been excellent.
“Sergio is irreplaceable for our fans, for this club, for the best moment in the history of this club, so it's difficult [for Gabriel Jesus].
“Sergio's got one more year here and we need good back-ups. But Sergio and Gabriel have an incredible relationship, they are really good."