Hi :wave:
I imagine neither are spayed as they are so young?
With rabbits you can't just plonk them together, the older rabbit has had her territory invaded and doesn't like it.
What size is the cage? Shop bought ones are never big enough and rabbits need a space of at least 6 x 2 x 2, but for indoor rabbits a puppy pen is good. Of course they need time outside it as well. Maybe shove loads of hay in to keep one or the other occupied.
Are you sure they are both girls? Definitely keep them separate as one may well be a boy. The older one may still be aggressive with you if you have been with the other because she can smell her but when the hormones have died down after a spay it should get easier.
My advice is keep them well away from each other, have them spayed when they are old enough and wait 6 - 8 weeks then you can try bonding them. I will warn you though, female/female bonds don't always work but that's not to say it won't. The best pairing for rabbits is a neutered boy/spayed girl. You might find a rescue near you that will help with bonding or finding them both partners.