Kim Kardashian is on high alert after Justin Bieber fans have told her to back off, the pop star belongs to them.

"Seriously Biebs! I'm getting death threats from your fans! This is unbelievable," Kardashian twittered Tuesday.

The two met Saturday night at the White House Correspondents' dinner in Washington, D.C. Bieber took a photo of the two of them together and referred to Kardashian as his girlfriend. Kardashian tweeted she had "Bieber fever."

The Stratford, Ont.-native's fans have always been a little fanatical.

Bieber has had more than one mall appearance cancelled after thousands of screaming girls showed up to see him. During a recent trip to Australia, his baseball hat was stolen and his mother was knocked down when he arrived at the airport. He also had to cancel a show in Sydney, Australia due to rowdy fans.

Bieber called for calm on Wednesday.

"Ladies, calm down. Kim Kardashian is a friend. A very sexy friend, but a friend. No need for threats. Let's all be friends and hang out," he tweeted.