Access REST service methods in sharepoint hosted apps in sharepoint 2013

Hi,

I am facing an issue with sharepoint 2013  app(sharepoint hosted App). I have a rest service method developed using VS2012. When i access the url from any web browser it gives the result. The same url i am using in my App.  when i request the REST service method i am getting an error "Access Denied".

My Code to call the REST the service

$.ajax({
            cache: false, url: "http://xx.xx.xxx.xx/rfrest/rfserver/rfserver004/testget", type: "GET",
            contentType: "application/javascript",
            dataType: "json",
            error: function (xhr, status, error) {
                alert("Error" + error );
            },success: function (data) {
                alert("Success:" + data); }  });

Why i am getting "Access denied" error while accessing the REST service from my sharepoint 2013 selfhosted app? How can i resolve this issue?

Any help can be  appriciated.

Thanks in advance.

Regards,
Kiran