Speculation about the couple's relationship began earlier this month after Rihanna was seen leaving the Two and a Half Men star's house in the early hours of the morning.
Later reports suggested that Rihanna had been dating Kutcher for two months.
However, speaking at a London press conference for her movie Battleship, Rihanna denied the reports when asked about them.
"Wow, how disappointing was that question," she said. "I'm happy and I'm single, if that's what you're really asking."
Battleship opens in the UK on April 11 and May 18 in the US.
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Take a look at Rihanna and the rest of the Battleship cast at their London photocall below: