The British actor admitted that his casting in the fan-favourite role polarised fans of Suzanne Collins's novels.
"There was a huge backlash," Claflin told Future Radio 107.8.
"Some positive and some very negative. You know, people were sort of saying they wanted to kill themselves and that I wasn't anywhere near good-looking enough."
Claflin went on to discuss the rigorous physical training he underwent for the role.
"You have to keep focusing and working hard, and the moment you channel that out I just had fun really. And it was hard work, it was definitely, definitely hard work.
Photo gallery - The Hunger Games: Catching Fire:
"I didn't really have a life ,but when I was on set there was a great dynamic between the cast and crew and when you're on a set in the middle of Hawaii, you don't really care about what other people think.
"I enjoyed the moment when I was in the moment."
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The Hunger Games: Catching Fire will be released on November 22.
Watch the trailer for The Hunger Games below: