If its electric and its really annoying or taking away from the track then its all about playing technique. Practice the part until you can play it without string noise and re-record. There are certain kinds of De-essers and EQ's which may or may not lessen the string noise but will also effect the sound of the instrument. A De-esser is your best bet but the very best is to learn to play without it.

Agreed... It's mostly a matter of technique. Although if the offensive noise is "finger squeak," (that zipper noise you get from running a fingertip along a wound string), you can mitigate it a bit on future recordings by using a lightly coated string, like Elixirs. I like them a lot on acoustic guitars, but finally went back to uncoated D'addario XL's on electrics.

You could also try recording the part on a guita strung with flatwounds, but that might be a bit extreme. And changing strings is no substitute for learning to play the part they way you want it.