We were driven out of necessity. You say you come in peace now. Sure you will. For a while. Then, when you're strong enough, you'll close in.
Some human always wants to be on top, to dictate and rule a warlike nation.
We've watched your race for thousands of standard years, and that's always how it works out. We really had no choice if we wanted to protect the otherwise peaceful unity of intelligent life. That's the reason we stopped your communications to Earth. Given any warning, of course, the humans would have retaliated against us, and our ships and many of us would have been lost needlessly before we could overcome your race. And I'm sorry, but your ship must be destroyed now.