A report claims iCloud users have been targeted in China by hackers seeking personal information.

The hackers managed to put their own websites between users and Apple's iCloud server, while retrieving data and potentially gaining access to personal user information, Chinese web monitoring group Greatfire.org wrote in a blog post.

Greatfire.org, which conducts research on Chinese Internet censorship, alleged government involvement in the attack.

"The attack on iCloud is apparently very big and very organized, so Apple should worry ... somewhat," said Pete Pachal, editor at Mashable.

Apple CEO Tim Cook discussed user data security in Beijing with a top Chinese government official, the official Xinhua news agency reported.

"The Chinese government has been implicated in many cyberattacks, so Apple obviously shouldn't give them any more access to iCloud security tools or information than is necessary to protect against these attacks," Pachal said.

He says it's up to the user to use security tools available to avoid getting hacked.

"Basically, if you're logging into iCloud via a browser, and you see anything suspicious—and it should be pretty obvious, like a browser window that says 'this site isn't safe!'—navigate away immediately," he says.