Hacking notice

That was not a popup, it was a page designed to look like a popup, and it was a phishing scam. When such pages appear do not interact with them, do not tap anywhere on the message. Instead tap the overlapping squares at the bottom right on the page, then tap the ‘x’ to close the page. See→Avoid phishing emails, fake ‘virus‘ alerts, phony support calls, and other scams

Close Safari and forget about the message. You haven't been hacked.

If my first post doesn’t solve the problem, see this user tip→Dealing with Safari popups that do not go away | Communities