'American Idol' Star Nikko Smith -- That's NOT My Penis ... In 'Love & Hip Hop' Sex Tape

Former "American Idol" finalist Nikko Smith wants the world to know ... he is NOT the Nikko Smith who stars in a sex tape with "Love & Hip Hop" star Mimi Faust -- but he's not exactly embarrassed by the mistaken identity.

Nikko -- who placed 9th in Season 4 -- tells TMZ, his phone has been ringing off the hook with calls from concerned friends and family members who read about a Nikko Smith's sex tape. He says fans have been tweeting him non-stop too.

'AI' Nikko says he's never dated, or even met Mimi Faust -- but adds he's cool with being compared to her boyfriend -- mostly because sex tape Nikko's hung like a moose.

He tells us, "There could be worse things linked to my name. At least the guy didn't murder someone."