It is violence whether they broke the law or not. We have as a society mostly deemed it to be acceptable violence. It doesn't mean that it's not violence though.
You're really saying that forcing someone to the ground at gunpoint, handcuffing them, and dragging them to jail where they'll be locked up and can't leave isn't violence?
You're changing the goal posts to redefine "arrests." To arrest someone is to enforce the law. You can be peaceably arrested, unless you resist arrest, which is further violating the criminal code.
A peaceful arrest is still done under the threat of violence though and is still violent. By this logic if I go to a bank with a gun and say, "give me all your money" and they comply without a fight it's not violent?
Edit: plus my first comment described a peaceful arrest, not someone resisting.
