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="Aktivace2.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="754" ns="6" title="Soubor:1.GIF" />
      <page pageid="944" ns="6" title="Soubor:10years new.png" />
      <page pageid="329" ns="6" title="Soubor:250px-Geocoin usa.jpg" />
      <page pageid="870" ns="6" title="Soubor:4535f084ac 93701247 o2.jpg" />
      <page pageid="437" ns="6" title="Soubor:AW neviditelné.jpg" />
      <page pageid="438" ns="6" title="Soubor:AW viditelné.jpg" />
      <page pageid="549" ns="6" title="Soubor:AbandonedBuilding-no.gif" />
      <page pageid="550" ns="6" title="Soubor:AbandonedBuilding-yes.gif" />
      <page pageid="714" ns="6" title="Soubor:Accept this challenge.PNG" />
      <page pageid="45" ns="6" title="Soubor:Aktivace1.jpg" />
    </pages>
  </query>
</api>