Mbappe, who scored 21 times in all competitions for PSG last term, has netted three times in five appearances for France at this year's tournament.
The 19-year-old netted a brace against Argentina in the round of 16, and was also in impressive form against Uruguay on Friday, with Les Bleus winning 2-0 to book their spot in the semi-finals.
Blanc has lavished praise on Mbappe, but has insisted that the nation "must be patient" when it comes to the development of the teenager.
"My opinion's not changed on him for 10 months: he's a phenomenon," Blanc told Le Parisien. "That's not to say he'll make us win all the time. He's young. He's still going to misfire sometimes – as little as possible, I hope for him and the France team.
"We must be patient with young players. But he's got more than talent. He's a guy who can scare defenders. The whole team benefits from the fear that the opposition have for him. That's good for the collective.
"At 19, you can't have everything. It's not possible. I hope that he won't be perturbed. I hope we'll see the fullness of his talents for a long time."
France will face Belgium in the semi-finals of the 2018 World Cup on Tuesday night.