How important are these interactions? Coming from someone who's had a GSD that didn't enjoy kids, and lived a lifestyle that never included them either, I'd say management is a simple solution. But now, decades later I need my current GSD to not only tolerate them, but accept them and be gentle with them, since my neighborhood and extended family includes children.
My dog barks at children when they're running around, but he's good about quieting down on command and he's able to run with them without jumping on them - so long as they're not swinging toys overhead, lol. But never has he growled at them, and this would really concern me. That's not a good sign. Not to say it can't be overcome, but it's a tricky situation for sure.