Is it safe to download MacCleaner to remove virus?

It's a scam, do not bite!

Follow these steps to remove the pop-up:

Force Quit Safari ( command + option + esc keys).Then restart Safari holding the Shift key. If you still have problems Empty Caches (Safari menu > Preferences > Privacy > Remove all website data. (This will also remove history if you do not want to remove History open Safari Preferences > Advanced and check mark “Show Develop Menu” then choose “Empty Caches” from Develop Menu ).

Then go to Safari Preferences > Extensions and check there. If there is an extension delete it.

If the problem persists then download and run Malwarebytes. Malwarebytes was developed by one of our own colleagues here in ASC and is about the most proven anti-malware software for Mac.

You're welcome.

No Anti-Virus software or so-called “cleaning” apps are needed or recommended for Mac OS. They can conflict with Mac's own built-in security. At best they will slow your Mac by using unnecessary resources and at worst will bork your entire system.