Looks like babies of predators not agressive and it is intended. But only with baby lions there is a strange thing.

If i, in survival mode, without god mode enabled get close to baby lions, they will produce attack animation, but they don't really attack actually, until i hit them first.

Here is video presentaion (maybe a bit laggy, sorry):

https://dl.dropboxusercontent.com/s/b2lmwo144d6r7r8/kZO0IUI7R4.mp4

Version: MC1.12.2-1.6.0.156