How to refuse a friendly match when not online?

Please !
My players often injured due to unwanted friendly match. I want to automatically give the friendly match when I'm not online. How can I do ????

You can't do anything... talk with them and ask them to don't put friendly game with you.

Un-friend them - they only accepted your friendship so they have someone to play friendly games with and get your presents everyday - assuming you send them any. I have 20 friends and none of them challenge me in friendly games - unless I talk to them before.