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="gateway_view.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="164" ns="6" title="File:12400 front.png" />
      <page pageid="136" ns="6" title="File:61000 cmm diagram-desc.png" />
      <page pageid="133" ns="6" title="File:61000 front panel.png" />
      <page pageid="135" ns="6" title="File:61000 front panel description.png" />
      <page pageid="175" ns="6" title="File:61k global cmds.png" />
      <page pageid="74" ns="6" title="File:chkp mgmt ha sync error.png" />
      <page pageid="122" ns="6" title="File:chkp vrrp cluster config-1.png" />
      <page pageid="121" ns="6" title="File:chkp vrrp rule.png" />
      <page pageid="230" ns="6" title="File:cp mgmt api enable all IPs.png" />
      <page pageid="229" ns="6" title="File:cpportsr77.png" />
    </pages>
  </query>
</api>