@ryanpq
ok. i understand your point.
i found that from nginx own blog though.
https://www.nginx.com/blog/9-tips-for-improving-wordpress-performance-with-nginx/
Check Tip 8

and after writing in their blog, one of their mod asked me to escape the second dot with a back slash.

location ~* ^\/upload\/directory\/.*\.(html|htm|shtml|php|js|swf)$ {
    deny all;
}

but unfortunately i didnt tried with above pattern in my existing project. but will give a try on my next project as it looks important feature to me.

thanks for your response anyway.