You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allimages gaicontinue="IPhone3G_Flex.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="541" ns="6" title="Soubor:107-178-thickbox.jpg" />
      <page pageid="540" ns="6" title="Soubor:3ghbflex.jpg" />
      <page pageid="542" ns="6" title="Soubor:Apple-iphone-5s-home-button.jpg" />
      <page pageid="1350" ns="6" title="Soubor:Apple Genius Bar.jpg" />
      <page pageid="1353" ns="6" title="Soubor:Apple Premium Reseller.jpg" />
      <page pageid="1354" ns="6" title="Soubor:Apple Premium Reseller APR.png" />
      <page pageid="148" ns="6" title="Soubor:Apple logo black.svg" />
      <page pageid="459" ns="6" title="Soubor:IPhone2G.png" />
      <page pageid="460" ns="6" title="Soubor:IPhone3G.png" />
      <page pageid="461" ns="6" title="Soubor:IPhone3GS.png" />
    </pages>
  </query>
</api>