API – Magento SOAP API Not Working on Secure URL

I have facing issue on Magento soap api connection whenever try to use https as secure url..

My magento system verson CE 1.7 and soap version 1.

System Url setup is

Secure url is  https://www.example.com/
Unsecured  is  http://www.example.com/'

When i am changed secure to http://www.example.com/(With out https)

Then the soap client is working properly.

Also,when secure is https://www.example.com ,it
throw below error:

SOAP-ERROR: Parsing WSDL: Couldn't load from
'https://www.example.com/index.php/api/soap/index/?wsdl' : failed to
load external entity
"https://www.example.com/index.php/api/soap/index/?wsdl"

My code is

try{

$cli = new SoapClient('http://www.example.com/index.php/api/soap/index/?wsdl');
$session = $cli->login('marketplace_usr', 'ezvendorplus');
$result = $cli->call($session, 'catalog_product.info', 10887);
var_dump($result);
}
catch(Exception $e){
    echo '<pre>';
    var_dump($e);
    }