Even as he fires, Chewbacca responds to each roar on the tigers' part with one of his own - standard wookiee battle cries, you know how it goes with the warrior races. That's how you handle aggression displays, okay? You just do better ones yourself. If you're a wookiee, anyway.

Of course, now that Han and Rey both have blasters in hand, that opens Chewie up to intercept one tiger as it gets in too close. It's better if he handle them at close range than one of the humans, after all.