Ranieri said that he saw improvement from his side in the second half, but not enough to warrant them getting anything from the game.
"I think that Reims deserved to win," Ligue1.com quotes Ranieri as saying. "If Reims were better in the first half, I think that we played better in the second half. Reims were a bit lucky but that is football.
"It was a good match and my players did good things. I am very satisfied because it was the first time these players had played together. I am satisfied with the way my players played, but not by the result. Naturally, Monaco played to win, as always, but Reims were good.
"I wanted us to go through so that those who have not been playing much could get more game time. But it doesn't matter, the priority is the league and making sure we qualify for the Champions League. It will be a really big game on Sunday at Lille. I am already thinking about what team to play."
Monaco are currently level on points with Paris Saint-Germain at the top of Ligue 1.