Your Mac says it's infected right after you clicked a Google ad — now what?

A browser pop-up that claims your Mac is infected is scareware, not an Apple warning. Do not call, download, or interact with it; force quit the browser if needed.

Do not call the number, download a cleaner, or click anything in the warning. Apple and Microsoft do not diagnose infections through browser pop-ups. If the page traps the browser, press Command–Option–Esc, select the browser, and force quit it; on Windows, use Task Manager.

Reopen without restoring the suspicious tab, update the system and browser, and run the security tool already built into or trusted on the device. Then report the ad through the search platform. If you already installed software, paid someone, or shared account details, disconnect the device from the network and contact the affected bank or service through its official channel.