stop river activity access from guest or not logged in


please tel me how to stop guest to  see activity page. I have private river 1.8 plugin in my site it remove all tab from site user but if somebody types in adress bar "" all activity of site member reviels there. I want to stop access for not logged in or guest members my activity and user profiles. I dont want to use login required plugin because all contents of my site are public.

I have searched for this on google but do not find any usable metarial.

please help