Apple Security

That is fake/scam trojan virus message. The object of that message is to get you to click on "Remove Virus" and then have you log on to a fake site with your Apple ID and Password. This will your credentials compromised. Nothing to do with a virus at all.

How do you know if that message is legitimate or not? It is nearly impossible for your iPhone to get a virus or get hacked unless your iPhone has been Jailbroken.

Some more reading on scams/phishing below-

All about scams and phishing -

Beware of ➔ Phishing & Other Suspicious Emails 

Know how to ➔ Identify legitimate emails from the App Store or iTunes Store 

Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams ➔  Use these tips to avoid scams and learn what to do if you think your Apple ID has been compromised.

Axel F.

It is not legitimate. All such messages are scams from criminals. Close the offending page and avoid sites that are involved in such bogus advertising tactics.

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support