@Atif have you tried the following..
Go to Privacy Settings > Block Lists > Block app invites. Type the names of friends you want to block from sending you app invites and press enter. Once you block app invites from someone, you'll automatically ignore future app requests from that friend. To block invites from a specific friend, click the "Ignore All Invites From This Friend" link under your latest request.
- Click on the top-right dropdown button > Privacy Settings > 'Ads, Apps and Websites' Edit settings > And then in the 'Apps you can use' section click on 'Turn off..'
Turn off your ability to use apps, plugins, and websites on and off Facebook. After you turn this off, we will not store information about you when you use apps or websites off Facebook.
WARNING: This will disable all your current apps (including all sites where you have used FB to login) and should prevent you from getting further app request.
Let us know if it works as expected.