jQuery(document).ready(function($) {
  $('.nav-tabs > li > a').on('click', function(event) {
    //avoid <a> tag to load his href
    event.preventDefault();
    //getting the main subjects
    var id_of_selected = $(this).attr('load-in');
    var link_to_load = $(this).attr('href');
    var iframe_to_load = $(document).find('#' + id_of_selected);
    console.log(iframe_to_load);
    //make the magic
    if (iframe_to_load.length) {
      iframe_to_load.attr('src', link_to_load); //this fires the link to destinated iframe
      iframe_to_load.parent().addClass('active'); //this make the parent div container of iframe visible
    }

  });
});

.tab-pane {
  display: none;
}
.active {
  display: block;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="nav nav-tabs">
  <li class="active"><a data-toggle="tab" href="https://www.google.com/maps/embed?pb=!1m14!1m12!1m3!1d11173.933562701173!2d12.2363393!3d45.560717000000004!2m3!1f0!2f0!3f0!3m2!1i1024!2i768!4f13.1!5e0!3m2!1sit!2sit!4v1452004351715" load-in="iframe1">WORKING!</a>
  </li>
  <li><a data-toggle="tab" href="http://www.youtube.com" load-in="iframe2">First Menu</a>
  </li>
  <li><a data-toggle="tab" href="http://www.facebook.com" load-in="iframe3">Second Menu</a>
  </li>
</ul>
<div class="tab-content">

  <div id="home" class="tab-pane fade in">
    <iframe width="200" height="200" style="width:200px;height:200px;" id="iframe1" src=""></iframe>
  </div>

  <div id="menu1" class="tab-pane fade">
    <iframe id="iframe2" src=""></iframe>
  </div>

  <div id="menu2" class="tab-pane fade">
    <iframe id="iframe3" src=""></iframe>
  </div>

</div>