The duo converted 12th and 17th places on the grid to top-six finishes, using great race pace to move through the field with a series of passes on rivals and a sharply-executed two-stop strategy.
"I am very happy for the team that we have managed to get a good result again. We have been unlucky in the two most recent races, and also had a bad qualifying yesterday," said Kobayashi.
"The performance of our car, especially in the dry, is really strong. If we only had qualified better we could have achieved even more today.
"At the beginning of the race it was a bit difficult on the medium tyres, but our strategy was good. Considering where we came from, 18 points is an excellent result."
Perez said he had been hampered by a possible puncture so could potentially have gained even more ground.
"My strategy was a little bit compromised because I had to do my first pitstop a bit earlier than planned," he said. "I felt something strange on the left hand side of the car - perhaps it was a puncture - but I don't really know yet what it was. This obviously meant we had to extend the later stint and I ended up with quite old tyres."