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="Agresor.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="5164" ns="6" title="Soubor:01 psi start.png" />
      <page pageid="5165" ns="6" title="Soubor:02 psi general menu.png" />
      <page pageid="5166" ns="6" title="Soubor:03 psi skype services.png" />
      <page pageid="5167" ns="6" title="Soubor:04 psi skype account.png" />
      <page pageid="1551" ns="6" title="Soubor:05http connect1.png" />
      <page pageid="1552" ns="6" title="Soubor:05http connect2.png" />
      <page pageid="1553" ns="6" title="Soubor:05http pooling1.png" />
      <page pageid="1554" ns="6" title="Soubor:05http pooling2.png" />
      <page pageid="1999" ns="6" title="Soubor:3282606.jpg" />
      <page pageid="2142" ns="6" title="Soubor:40px-Emblem-important.svg.png" />
    </pages>
  </query>
</api>