E! Online says hackers compromised its Twitter and text messaging accounts, sending out erroneous news alerts about Justin Bieber and Angelina Jolie.
The Syrian Electronic Army claimed responsibility for Saturday's hack.
E! Online said it was working with Twitter to correct the issue, and that an investigation into the attack was underway.
The SEA has taken credit for a string of Web attacks on media targets it sees as sympathetic to Syria's rebels, including the BBC, Al-Jazeera English and the Guardian.
The group claims to have hacked the Twitter feed of The Associated Press last month.