Cilic was 6-3 3-0 down when he burst into tears on Centre Court.
He had medical attention from a doctor at the end of the second set after a medical timeout was called.
The Croat explained: "It was just emotionally that I knew on such a big day that I'm unable to play my best tennis, in physical, and in every single way.
"That was just a little bit combination of all emotions because I know how much it took for me to get here.
Marin Cilic was visibly emotional on court midway through the Wimbledon final
Roger Federer beat Marin Cilic in straight sets to win his eighth Wimbledon title
It was just emotionally that I knew on such a big day that I'm unable to play my best tennis
"It was just a feeling that I knew that I cannot give my best on the court, that I cannot give my best game and my best tennis, especially at this stage of my career, at such a big match.
"It was very, very difficult to deal with it. That was the only thing but otherwise, you know, it didn't hurt so much that it was putting me in tears.
"It was just that feeling that I wasn't able to give the best."
Cilic revealed he resorted to anesthetics before the game to try and give him a shot of SW19 glory – but even that was causing problems.
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Marin Cilic breaks down in TEARS during Wimbledon 2017 final Sun, July 16, 2017
Marin Cilic broke down in tears during the Wimbledon final against Roger Federer.
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He said: "We even tried with some anesthetics just to block the pain but in that area it's very difficult because it's hard skin. It helped, but I still felt some pain.
"Even when I was warming up for the match, I was trying to test myself in exercises with change of direction.
"Really I was too slow basically to react. I knew that it's going to be difficult. But I tried."