Solution:
I have fixed it, So basically I need to prevent the direct access to a folder which is inside the wp-content/uploads folder. So I just created .htaccess files inside that folder and put following rules and it’s working fine now. Thanks all
RewriteEngine On
RewriteCond %{HTTP_COOKIE} !^.*wordpress_logged_in.*$ [NC]
RewriteRule ^(.*)$ - [R=403,L]