iframe not working in my site

hello every one !

my problem is , now i change my hosting shared to vps all things are did well .

then i add new post it’s also working fine every function working good , i think it’s major problem for me ( THE PROBLEM IS )

in the post i add ( iframe tag and iframe shortcode this will getting 403 error ) i add all tag and code apply in the post nothing affect the post IFRAME only 403 forbbiden

pls Help me to find out the solution

i know my english is very poor but i think many geeks are here to resolve problem