France emerged victorious by a 1-0 scoreline thanks to a second-half header from Samuel Umtiti, and Didier Deschamps's team saw out the rest of the game with Belgium struggling to create clear-cut opportunities.
However, Courtois feels that France played negative football, claiming that Belgium were the better team during the tie in St Petersburg.
The 26-year-old told beIN Sports: "I wouldn't say the team in front of us was better than us.
"The team in front of us has defended well with 11 players, 35 metres before their goal and they've done this the whole tournament. Against Uruguay they score with a free kick. Today a goal from a corner. Pity, but that's football.
"It depends on the details. Every team plays to their strengths. Our strength lies with playing football. Their strength is defending and counter-attacking with [Kylian] Mbappe who is very fast. But it's a shame, you see."
France had 19 shots on goal on Tuesday night, more than double the nine chances which Belgium created.