Sure, because all of politics is pretty much a gimmick anyways. Most politicians say what people want to hear and talk about what the people want to talk about when elections are in progress, but not as much once they're in office. Once they're in office, they pretty much do their own thing. And politicians tend to use other people and situations as virtual punching bags anyways, so if an attack is made on a politician, at the very least it'll expose whoever made the attack as the person that they really are.
Political attacks are justified advertisements because candidates need to distinguish themselves from other candidates. One easy way to do this is to demonstrate negative things that another candidate has done in order to make him or her seem like a bad choice. While voters tend to dislike political attack ads, they are justified because candidates must do what it takes to secure the position.
The attacks for political matters or reasons have been obviously used by more powerful countries to take advantages or to show off their power to smaller countries. Particularly, attack in Paris in November 2015 was used to ban Syrian even though no evidence has been found to prove that Syrian were involved in the chaos.
I'm not sure what you mean by political attacks - if you mean verbal attacks from one politician to another, then I'd say that's basically just a part of the job. Politicians are aware that people don't agree with their policies, sometimes quite vociferously. If it's physical, then obviously that's not okay - no physical attack is.