security warning

As KiltedTim mentioned, this is a scam pop-up from a website. Some websites use advertisements that include JavaScript functionality to perform this type of function - it’s a scare tactic to get the user to perform an action. I recommend investing in an ad-blocking extension for Safari.

No. It's a scam popup from whatever web site you were visiting. It did not come from Apple.

Or better yet, don't patronize web sites that allow deceptive predatory advertising...

Best advice I’ve heard in a while! Thank you!