% pandoc -t html -f rst --wrap=none
.. image:: http://url.to.image/foo.png
   :align: left
   :height: 100px
   :width: 200 px
   :scale: 300 %
   :alt: alternate text
^D
<p><img src="http://url.to.image/foo.png" alt="alternate text" class="align-left" width="600" height="300" /></p>