In "Galaxy's Child," the Enterprise comes across a space-dwelling organism that is with child. The organism fires a stream of radiation at the ship, and, to defend himself, Picard orders the firing of phasers. This kills the creature, much to the chagrin of the captain.
Why not try hailing it first? It may be unlikely to succeed, but it can't hurt to give it a shot. After all, in an earlier encounter the Calamarain, a species even less like humans than "Junior's" species, attempted to communicate with the Enterprise, though its message could not be translated on the spot.