Thanks for writing. The critters you're seeing are probably fungus gnats. The good news is that they do little to no damage to plants. The bad news is that they're annoying.
Fungus gnats thrive in moist soil, so decreasing the amount of water you give your plants should help reduce their populations. Because the adult fungus gnats lay eggs in the moist soil, you can also reduce populations by putting an inch or two of sand over the soil in your pots. This sand will create a dry barrier from the soil.
---Justin, Senior Garden Editor, BHG.com