how to block "screensaver.app" pop-up in Safari 12.1.1

This worked! I deleted Safari history, I emptied cache, I found "Flash Player" file in Applications and dragged to trash can and emptied, I then went to Malwarebytes and downloaded. Ran scan. found lots of "Mac Ad cleaner" files and other phony files. Got rid of them all. Now Safari works again without that incessant "Screensaver.app wants control of safari.app" popup! Thank you for the solution to this problem!

See if anything here helps.

pop up blocker wont turn off - Apple Community

Safari – Popup takes over

Safari – Popup takes over (2)

Popup remover – Scam Zapper

If the pop-up reloads, force quit Safari (command - option/alt - esc) and reopen with the shift key held down. If that doesn't work, disconnect from the Internet, go to Safari/History and delete the website. Quit and reopen with the shift key held down. Then reconnect to the Internet.

Safari -Tech support scam pop-ups

I had the same issue. I just got off the phone with Apple support and they said to install Malwarebytes (I put the link below) select download in the top right corner. Before letting that scan Go through and delet all internet history, and cache. Also go through your downloads and delete any "Adobe flash". Then let Malwarebytes scan your computer and then delete anything that it finds.

https://www.malwarebytes.com/