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Yes.That is a SCAM message. Follow the steps below to fix the issue.
Press and hold down the Power button and Home button at the same time until it shows the Apple logo. When you see the Apple logo, release the buttons and let your iPhone boot. Then without opening Safari, goto Settings > Safari. Tap Clear History and Website data.
That should remove the scam message from your iPhone.
Please let me know if that didn't work, so we can continue troubleshooting.