I happend with electric gituars too, you just cant hear it over the amp.

There's nothing you really can do to stop it cos it's part of the acoustic sound, although, does your acoustic have heavy strings cos light strings might reduce it a bit.

Heave strings are harder and therefore you have to press down on them harder so when changing cord you still have a little pressure on them. Like it said, lighter strings might reduce this

You can just play classical guitar as they have nilon strings [which have no ridges]

Also like alexgc said, if you listen to any acoustic set, like MTV Unplugged. I accually kinda like the sound a bit.