Alexandre Lacazette's brace helped Lyon to a 3-0 win over Toulouse, lifting them above Marseille and into first.
Fournier said it was too soon to discuss his side's title chances, with 18 matches still to play in the league.
"It is much too early to draw any conclusions. The end of the season is too far away to make any claims," he told a media conference.
"We will only talk about the title if we are in a good position when there is five or maybe six games to go before the end of the season.
"Besides, when we look back in the league table, we can see big teams chasing us, teams that have invested millions and have plenty of stars in their ranks, so we can only be humble and modest."
Nabil Fekir was the other player on the scoresheet for Lyon, while the midfielder also set up Lacazette's opener.
Fournier said the duo's combination had come as a shock.
"It is a surprise to see them at this level. To be honest, we did not expect it at the start of the season," he said.
"But that's the beauty of the game, sometimes you are lucky enough to find the right chemistry.
"Those two players find themselves very well on the pitch and until now, their partnership has been a success."
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