Children will be children, and lions will be lions. The girl can't be blamed for not understanding how she taunts the lion. Nobody can say the lion is doing any wrong by acting upon his instincts.
But perhaps in that moment captured on footage, the girl realized that this cat is not the same as the friendly felines who live in human homes. Unlike his domesticated counterpart, this lion still feels the full force of nature guiding his actions, which begs the question of why such an animal should be held captive and subject to visitors who, even if accidentally, point at and taunt him.
Captivity is an unnatural and stressful environment for any animal. The most direct way you can keep animals out of these places is by not supporting the institutions that keep them there. To learn more about efforts to keep wildlife in the wild, check out the Born Free Foundation, which aims to rehabilitate previously captive animals back into the wild.