Don't click on the link.
Go to Help > About Firefox and check that version 32.0.1 is shown. (If it isn't, it will either automatically update or offer you a safe link for you to do so).
Assuming that we've definitely established that the message you're seeing is false, then it must be generated by malware (which is trying to trick you into clicking on a link so that something really nasty ends up on your computer. Download, install and run the free version of Malwarebytes Anti-Malware to get rid of it:
https://www.malwarebytes.org/antimalware/
(NB: When installing it, take care to de-select the pre-ticked option to take a free trial of the 'Premium' version. Don't be surprised if a scan takes ages to run; that's normal. When malware is found, use the 'quarantine' option to get rid of it).