Depending on the type of dogs you have...a spray bottle works great. If they go after the kittens or cats tell them no in a firm voice and give them a squirt from the spray bottle.  This works on almost all dogs...except labs as they love water and think it is a game. 

As I have learned in dog training classes, with your dog on a lead, use the clicker trainer.  That always seems to work.  A good firm voice would work as well.  Get your dog in a sit postion on the lead, sit and stay, bring the cat nearby and if the dog lunges, tug at the lead and say, "Leave It", have him sit.  It may take several times over and over before any results but as soon as he is calm, even for a second around the cat, praise, praise praise.  You want him to know that is what you want him to do.  Keep removing the cat, have the dog sit, Tell him to "leave it" when he wants to chase the cat, pull him back to a sit and praise him.  This won't happen over night but you will find after a while that with patience on your part it will.  Dogs do want to please their masters.  I hope this helps.