How long has it been going on? If it's new, what change occurred in the household at that time e.g. person/cat moved in/out? - In a situation where a favorite person or animal is no longer there, a flower essence to help with abandonment or sadness can help. Also Walnut is helpful for transition issues. If on the other hand, a new person/animal moved in, then an essence e.g. Holly which helps with jealousy, might be better indicated.
Is there a particular animal your cat picks on? What is the underlying dynamic there? Is it jealousy? That would call for a different essence than say general rough play.
If none of the above are the case, and you just have a naturally high-strung cat, Lavender flower essence can give excellent results.For example, with young feral cats/kittens who are overwhelmed by new sights, sounds inside a house and "act out" for lack of a better phrase. Or cats/people w/ adrenal burnout where a person is tired and wired at the same time, so can't sleep but has no energy.A cat with a lot of baggage could well benefit from Lavender because the aggression is just disguised fear, dread, and fatigue.
If your cat is upset but not necessarily jumping around attacking other cats and dogs or displaying hyperactive behavior, I'd skip Lavender, and look at Sunflower as well as Violet. The latter is excellent for cats who seem to get lost in a group where the others have stronger personalities causing these guys to hang back. Meanwhile, they're feeling under-appreciated and unloved ready to act out at the first chance.