The musician, who received an Oscar for his score for The Social Network, will appear as Jack Barts, a vampire who slays the President's mum.
Speaking to fans on a Nine Inch Nails forum, he said: "The idea was a cameo-esque role that would be kept under wraps and be a surprise around opening night.
"I was considering this when I awoke a few days ago to the news I am now STARRING in ALVH (which is obviously not true). We both apparently forgot the internet existed AND THERE ARE NO SURPRISES anymore (sic)."
The band's frontman added: "So... do me a favour and act surprised, OK?"
Reznor is currently working on David Fincher's The Girl with the Dragon Tattoo.