The reigning champion has endured a rocky start to the season in 2018 but took pole for Mercedes in Le Castellet.
But as Hamilton was given the opportunity to take the plaudits, he decided to praise Leclerc for his stellar performance which saw him finish eighth for Sauber.
“I just saw before I went out that he was in the top ten going into Q3 which was very, very impressive to see,” he told reporters.
“Particularly with the all the pressures you could see.
“There’s a lot of pressure for him, being here in the South of France, so really good.
“[I’m] really happy for him, particularly in that car, he’s doing a great job with what he has and probably delivering more, which is what you would hope from a good driver.”
Vettel holds the lead in the Championship at present but could only manage third in France on Saturday.
And the German also heaped praise of Leclerc’s showing.
“I saw only on the screen that Fred Vasseur was pretty happy, so I thought one of his drivers did well in Q2,” added Vettel.
“I didn’t see [him] in Q3 but obviously eighth is an impressive result.
“I think they are still quite a long way behind with the car so I think for him, he’s doing the job. It’s good for him and good for Sauber as well, to be up there. And hopefully for them they have some chance to score points tomorrow.”