They could be either fungus gnats or black aphids - neither will do much if any harm to the plants and can usually be controlled with just water spray just as you did.

The mix for soapy water spray is 1T of liquid soap to 1 gallon of water and shake well. But it can be harmful to the plant if not used correctly: only lightly mist the bugs and not the whole plant, do NOT drench the leaves, and do NOT spray in the direct sun or the heat of the day.

Hope this helps.

Dave

I got those little fling gnats or flies to all over my new tomatoe plants too. I thought they might be a type of flying aphid. Not to sure but have seen something similar on my roses and sprayed very dilute all purpose insect spray and got rid of them.
gene