WKWebView automatically decide policy for embedded iframe url

In my case, I have website (that includes 3 button shared for Line, Twitter, Facebook). Everything was working well until I check the action link clicked inside webView.

My code have jumped from webView to shared links even I not click inside webView. (when it first load webView).

My code:

func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
 			if let urlMain = navigationAction.request.url {
                   if urlMain.host == "line.me" {                                                                      decisionHandler(WKNavigationActionPolicy.cancel)
				UIApplication.shared.openURL(urlMain)
            }
     decisionHandler(WKNavigationActionPolicy.allow)

}

Can you help me find the solution? All I want is when I first present webView, it not navigate to shared links, and it only work when I click on button shared in webView. Thanks you!