<?php
$user = 'username';
$pass = 'password';

$url = 'https://'.rawurlencode($user).':'.rawurlencode($pass).'@hostname.com:2003/index.php?api=json&act=domainmanage';

$post = array(
    'force_https' => 1,     // Action to trigger Force HTTPS update
    'do' => 1,              // 1 = Enable, 0 = Disable
    'domain' => 'example.com' // Domain name
);


// Set the curl parameters 
$ch = curl_init(); 
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 5); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 

if(!empty($post)){
	curl_setopt($ch, CURLOPT_POST, 1);
	curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post));
}
// Get response from the server. 
$resp = curl_exec($ch);

// The response will hold a string as per the API response method. In this case its PHP Serialize
$res = json_decode($resp, true);

// // Done ?
if(!empty($res['done'])){
    print_r($res['done']['msg']);
}else{
    print_r($res['error']);
}