Vettel was controversially handed a five-second penalty in Montreal, which meant he finished the race first but was immediately dropped to second position behind the chasing Lewis Hamilton. Ferrari teammate Leclerc had been gaining on the lead pair in the closing stages and finished just six seconds adrift of Vettel -- which became one second once the penalty was applied.
Leclerc said he had been pushing as normal, trying to catch Hamilton.
"I didn't know anything about it," he said. "The team didn't let me know that Seb had a five-second penalty, so I was just trying to push to try and catch Lewis up, but I didn't know about the penalty."
When pushed for an explanation, Ferrari team boss Mattia Binotto said the team simply forgot to tell Leclerc.
"We didn't [tell him]," Binotto said. "It has been a mistake from our side.
"I think we were very busy on the pit wall and simply we forgot. We should have done it but we didn't."
Leclerc went on to claim he would not have changed his approach had he known the punishment handed down to his teammate.
"I was pushing very hard to catch up," he said. "I saw they were fighting, I saw they were close at least. I saw also that we were quite quick and we were catching up, so I was just pushing very hard so if anything happened I had the opportunity to be as close as possible to do so. So no, it wouldn't have changed my approach."