People say this all the time, and it's true: our most likely military reaction to terrorist attacks probably is the basis of their strategy; they're not stupid, the response is predictable, and so why strike at all if you don't want a reprisal?
But it doesn't follow logically that military response is strategically bad for us! Just because ISIS wants us to do something doesn't mean we shouldn't do it. ISIS could be very wrong about wanting to provoke military escalation. In fact: it almost certainly is.
That doesn't mean that military strikes are good, or the right option at this point. It just means that saying "that's what ISIS wants us to do" isn't a dispositive argument.