England were seen as the favourites to progress to the final of the competition, and took an early lead in the semi-final when Kieran Trippier's free kick found the back of the net.
Modric told ITV: "We proved everything differently that people were talking. Especially English journalists, pundits from television, they underestimated Croatia tonight and that was a huge mistake.
"All these words from them we take, we were reading and we were saying 'OK, today we will see who will be tired.' As I said, they should be more humble, and respect opponents more. That's it."
Croatia will take on France in the final of this year's World Cup on Sunday afternoon.