403 Forbidden error when making an ajax Post request

My code is working fine on localhost(wamp server) but upon moving it to a shared hosting, I get error 403 (forbidden). I tried this first:

    $.post('login.php?login', { user_email: user_email, user_password: user_password, user_remember: user_remember }, function(data)
    {
     // Some code here
    }

Then I tried this:

var http = new XMLHttpRequest();
var url = "login.php?login";
var params = "user_email="+user_email+"&user_password="+user_password+"&user_remember="+user_remember;
http.open("POST", url, true);

http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

http.onreadystatechange = function() {
    if(http.readyState == 4 && http.status == 200) {
        // Some code here
    }
}
http.send(params);

But I still get this error:

POST http://domain_name/login.php?login 403 (Forbidden)

Any idea whats wrong?