If the kittens are perceived as part of the landscape then they won't bother them. Its the introduction phase that can be dicey. But once the kittens or cats are introduced and accept each other the Guineas will join in and will investigate things that the kittens are doing that they don't see often.
Example: My Guineas would encircle one of our dogs if he was laying on his back in the middle of the yard. Once they realize its just one of their dogs they go off and do their own thing.
I've got problems with my dogs killing my kittens and i think once they git older they can live on there own and take care of themselves.plus i have a coop with a kinda big run on it and i thought maybe i could put the kittens in with them so my dogs can't git to them and if the kitten grow up with the guineas it mite help so they don't kill them.
If you just plunk a kitten down in the coop the Guineas will kill it. Just as with chickens an introduction needs to happen. Put the kitten in a separate pen or huge cage while the Guineas get used to it. You also need to think about the rambunctiousness of a kitten that may not play well with the Guineas.
BTW, the dogs need some training. If you bring a new animal on the property and they kill it they are out of control and need to be taught where their place is in the pack. I have three 100 pound plus dogs, I have cats that sleep with them but don't let a cat that doesn't belong enter the property or they're after it.
Guineas don't kill anything at night. They're sound asleep as soon as it gets dark and sleep until dawn. You need to introduce the kittens to the dog and let them know you like them. Same goes for any new chicks or any animal you don' want the dog to think is an intruder.