add_filter('content_save_pre','iframe_save_pre');
  
function iframe_save_pre($content){
    global $allowedposttags;
    $allowedposttags['iframe'] = array('class' => array () , 'src'=>array() , 'width'=>array(),
    'height'=>array() , 'frameborder' => array() , 'scrolling'=>array(), 'marginheight'=>array(),
    'marginwidth'=>array());
  
    return $content;
}{"code":"rest_no_route","message":"URL \u3068\u30ea\u30af\u30a8\u30b9\u30c8\u30e1\u30bd\u30c3\u30c9\u306b\u4e00\u81f4\u3059\u308b\u30eb\u30fc\u30c8\u304c\u898b\u3064\u304b\u308a\u307e\u305b\u3093\u3067\u3057\u305f\u3002","data":{"status":404}}