Mobile Safari Redirects to App Store
Unfortunately regardless of Apple's efforts to curb websites redirecting users to the iTunes App Store, it still regularly occurs.

There is no 'setting' which enables / disables this 'feature', my only recommendation would be to ensure the "Fraudulent Website Warning" is switched on, having the "Block Cookies" setting on anything but 'always allow' and also testing weather turing off JavaScript support (under Advanced) helps in any way.