You have to be smart, if your going to be a war monger, expect to be embargoed. Or, be a war monger with 1 other large friend that you bribe, and use dipolomats to ensure your protection. city state allies can help you vote against it as well. When I am on a conquest victory, if I want to be avoid being embargoed, I will always try and be a host or a secondary, and introduce a legislation contrary to the world intrests, so they vote that down, and then I vote down my own embargo, to ensure passing.