Anyone who clicked on the ad was led to a page suggesting that their computers had been infected with malware.
The popup app appears to have been hosted on a Facebook page to avoid detection by Google's software that automatically identifies scams The malicious scripts can also put your browser on full screen and spawn pop-up messages that won't go away, essentially locking your browser.
The ad, set up yesterday, has since been removed from Google's Ad Sense platform.
A spokesman for Google said: 'This was an abuse of our platform.
The websites typically use malware in the form of script files like Java Script or HTML, which can display various fake error messages.
It encouraged visitors to call a free support line to resolve the problem.