The Office and Hangover star told The Playlist that reports he is to feature in the revived comedy franchise are mere speculation.
"I have no idea where that bubbled up," he told the website. "I don't know where that came from. It's nothing I know of."
Horrible Bosses scribes John Francis Daley and Jonathan Goldstein will write and direct the Vacation reboot. The movie is rumoured to focus on Rusty Griswold - played by Anthony Michael Hall in the 1983 original - and his family as they take a holiday.
Chevy Chase starred in the original Vacation movies alongside Beverly D'Angelo. The final entry in the original series, 1997's Vegas Vacation, was not released under the National Lampoon banner and received a lukewarm reception.
Helms recently revealed that he is hopeful a third Hangover film will move forward soon, describing it as "a work in progress".
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Watch the original trailer for National Lampoon's Vacation below: