index.html

<div id="cs_feedback_pane" ><!-- iframe here --></div>

<a href="javascript:void(0)" id="cs_panel_link" onclick= "loadIframe(); return false;">Load iframe inside div</a>

<script type="text/javascript">
function loadIframe () {
    var iframe = document.createElement('iframe');
    iframe.frameBorder=0;
    iframe.setAttribute("src", 'http://www.google.com');
    document.getElementById('cs_feedback_pane').appendChild(iframe);
}
</script>