are they white? they will probably be whitefly. You can get a spray to treat them, but treat all your plants and then repeat according to the instructions, as they will have laid eggs.

If they are black they could be fungus gnats. That is treated really by letting the compost dry out a bit.

Did you plant House Plant in Garden Compost? I find that a No! No!
I had this happen to me & found out I should have used compost for indoor plants, there are little eco-friendly yellow sticky traps you can buy from Thompson & Morgan
10 for £4.99 if the problem continues.
Good Luck xx

If it's the fungus gnats, a weak solution of hydrogen peroxide--I can't remember the exact proportions, but they are available online--or a product containing Bacillus thuringiensis israelensis, or beneficial nematodes will work on them. In my experience, the yellow sticky traps are a good preventative or diagnostic tool, but don't help much with an established infestation. Also, pour a little chlorine bleach down the sink and shower drains, since the little gits can colonize the plumbing, too! :(

Thanks this makes sense and will give it a go !

Thanks to you I have found some sticky traps on Amazon f which I am going to give a go