While he did not name Rihanna personally he did joke about how he has been romantically linked to "beautiful women" and he is not bothered by that as long as they are "beautiful". (Lewis Hamilton's Italian GP Victory Stands)
"Yeah, I'm single. I'm not attached to anyone. I'm a free spirit so I'm just going in with no plans to settle down any time soon. I'm going to focus on my career. I'm enjoying my music. I've been associated with some really beautiful women. I don't even mind, as long as they're beautiful women."