You can simply use confirm function:
'callback' =>'
function (){
if (confirm("Asking comething?")) {
jQuery.getJSON(
"'. $this->createUrl ( 'place/rating', array('ratingId'=>$model->rating_id ,'ajax'=>'rating')) . '",
{ val: $(this).val()},
function (data) {
if (data.status == "success") {
$("#rating_success_' . $model->rating_id . '").html(data.div);
$("#rating_success_' . $model->rating_id . '").fadeIn("slow");
var pause = setTimeout("$(\"#rating_success_' . $model->rating_id . '\").fadeOut(\"slow\")", 5000);
$("#rating_info_' . $model->rating_id . '").html(data.info);
$("input[id*=' . $model->rating_id . '_]").rating("readOnly", true);
}
}
);
}
}'