"Winning the Champions League's our main objective," he told Ligue 1.com. "We're all dreaming about that. But we have to be careful because sometimes we look like a different team in Europe.
"We have to understand that while the Champions League is a big competition, the league is just as important. Don't forget, Paris haven't won the league for 18 years!
"It's good to be top but we haven't won anything yet. Marseille and Lyon aren't far behind. We have to keep working hard to achieve our goal."
PSG are away at Saint-Etienne in Ligue 1 on Sunday.