Rafael Paulino

With this plugin you can place an iframe inside the TinyMCE text editor. 
You click a button in TinyMCE and a window appears to place the iframe data. 
Then just click on Ok and a shortcode is inserted with the iframe data and on the front the iframe is presented.
Com este plugin você consegue colocar um iframe dentro do editor de texto TinyMCE. 
Voce clica em um botão no TinyMCE e aparece uma janela para colocar os dados do iframe. 
Depois é só clicar em Ok e um shortcode é inserido com os dados do iframe e no front é apresentado o iframe.

Rafa TinyMCE Iframe

With this plugin you can place an iframe inside the TinyMCE text editor.

brajesh

Embed Iframe is a plugin that will let you embed iframe – an HTML tag that allows a webpage to be displayed inline with the current page, in a WordPress post. Although an iframe can lead to a complicated website, it can be very effective when used appropriately.
<h3>Usage</h3>
Use following tag to insert another page in post using iframe
<pre><code>[iframe url width height]
</code></pre>
e.g.
<pre><code>[iframe http://www.example.com 400 500]
</code></pre>

Embed Iframe

Allows the insertion of code to display an external webpage within an iframe.

Rafa TinyMCE Iframe vs Embed Iframe