Fake GM?

The site in question is most definitely malicious, Salcaz. Should you have visited the actual web page, please take some time now to scan your computer system for possible malware while the WoW launcher is open (some software recommendations may be found here: http://forums.worldofwarcraft.com/thread.html?topicId=1778038509&sid=1). Following, reset your Battle.net account password. If you entered in any account specific information, complete the above steps and then select a new email address for your Battle.net account and update it as soon as you can.

In the future, if you receive a message from a person purporting to be a Blizzard representative, do a quick check by right-clicking the author's name. If you receive the standard drop-down menu (with "Report Spam" option included), that's a sure sign that you are not speaking with a Blizzard representative. It's also important to note that Blizzard representatives will always have a blue "Blizz" symbol next to their name when communicating and, AddOns permitting, that conversations with these representatives will prompt a separate dialogue box.

Scamming messages like the one you've described may be reported using the aforementioned "Report Spam" feature. By selecting this option, not only will you alert our in-game staff to this message, but all characters on the author's account will ignored for the duration of your login session. :)