Vardy was largely ineffective in defeat at United and Leicester manager Claudio Ranieri withdrew the striker at half-time with their Champions League tie against FC Porto in mind.
“They're a very dangerous team in counter-attacks and Vardy is the best counter-attacking player in English football," Mourinho told Portuguese media.
“FC Porto shouldn't think Leicester are what they've done against Manchester. It's nothing like that.
“Leicester are a good team and Porto will have to play very well to beat them."