I don’t know how much room you have in the coop or outside, so I can’t give specific advice, but Mary nailed it. Set up a separate area where the new chickens can be housed for a while in sight of the others but separated so they can’t get to each other. That might be a pen in the coop if you have room, maybe something cheap like chicken wire since predator protection should not be an issue, or a dog crate or something like that with its own run outside. Let them get used to each other, then try it again.
With those ages, don’t expect the new girls to immediately start hanging with the older ones. Until the new ones mature enough to force their way into the pecking order, they will probably want to avoid the older hens. That’s perfectly normal behavior, the older hens outrank them in the pecking order because of maturity and sometimes aren’t shy about enforcing that especially when the younger invade their personal space. That mingling will come with time, usually around the time the younger start laying. At least that’s the way it works with mine.
What you are after right now is that the older stop going out of their way to attack the new ones. That’s a successful integration. Them merging into one flock comes later.