Crafted to cause a sense of panic, these attacks seem to have a list of valid and current iCloud users.
Clicking on the "Call" button will initiate a call to "Apple Care". For a charge on a credit card, the caller will load a "mobile device management" suite to prevent such attacks. Instead the mobile device management suite will enroll you in a suite designed to deliver malware to your iDevice.
Stories abound with friends, family, neighbors, and others falling for more and more sophisticated attacks.
When in doubt, which should be almost always, contact the vendor via normal or out-of-band means.
