Do you know what kind of plaster was used to create the texture? It would be helpful to know that.
To avoid the dust, and if it would work on the type of texture and plaster that has already been applied, you could get the sanding apparatus that people who apply drywall use to sand and suck up the dust, such as might be found on the following links that you will find on the following search.
Drywall Sander No Dust - Google Search
I am sure that there will be others who will come along to address your question. I am usually dealing with paints and the application of fresh drywall as well as textures. But, the textures that I apply are not very compact or dense. You could be dealing with something that is actually a thick and dense plaster for the texture, so drywall tools may not work.
Please be sure to wear the appropriate safety equipment, such as a dust mask and goggles, no matter what you do to smooth out the appearance of what is already there.
Thanks!