Coach Fernando Santos' first game in charge ended in defeat after Karim Benzema and Paul Pogba put the Stade de France hosts on track before Ricardo Quaresma's late penalty.
But Carvalho believes his side showed enough to have something to build on as they look to get their Euro 2016 qualifying campaign back on track against Denmark on Tuesday.
"I think it was an important game for us as we came into it off a defeat [to Albania] in our last match," he said.
"Now we have started something new and I think we are going to build up our confidence and improve.
"Denmark is an important game for us to try to win. I think everyone in our squad felt this was a good test and of course we were up against some great players, so that will help us to do well in Denmark."
While Benzema opened the scoring in just the third minute, his Real Madrid team-mate Cristiano Ronaldo came off with a suspected knee injury.
But Portugal attacker Nani said the result of the friendly was no indication of who was the better player.
"Today was not about who is better between Karim Benzema and Cristiano Ronaldo. We know who is better," he said.
"Today was a good game and that was what was most important for both teams."
