Vinaya Rule which prohibits on engaging in political activities There are many monks who are engaging in many political activities such as riots and other types of embarrassing activities in certain countries.

What are the Vinaya Rules on these? It would be great if sources are provided.
Bikkhu can advise laymen about  politics, for the example, see "Conditions of a Nation's Welfare" in mahāparinibbānasutta. 

And saṅgha means "group of bikkhu".

Another, all virtual (sīla), keeping-sīla (ethic) and avoiding-sīla (precept), are politic because of "10 purposes of monastic legislation:for the lastingness of the true doctrine", so all advising about physical action &amp; speech are politic, too.

However, bikkhu maybe offense vinaya, if the advising or action is wrong, conflicted with vinaya, such as ordering to kill or ordering to stole, etc.