Any Parisian restaurant will be child friendly for well behaved children and responsible parents. You problem is more than likely going to be finding ones open for dinner at an hour early enough to suit your children's schedule (you don't for a minute believe that you actually get to decide, do you?). Most Parisian restaurants don't open for dinner until 7-8 PM., which tends to be later than suitable for most kids. Your best bet will be to look around in the neighborhood of your hotel select local cafes that serve food through most of the day. They will also have less formalized menus, which will allow you to have a meal and a child to have a Croque Monsieur, omelette or crepe. Most will have menus posted out front to give you some idea of their selections.
As has also been suggested, there will probably be creperies about. One has been suggested on rue Saint Andre des Arts, Creperie des Arts (across from Corcoran's Pub at rue Git-le-Coeur) and there is another a bit farther down the street, Le Creperie Saint Germain at few doors down, near rue Seguier) But neither of these little places may do you any good, if your hotel is up in the 9th or out in the 11th arrondissements.
I t would probably also be a good idea to locate a supermarket somewhere in your neighborhood (or if you're driving to Paris, somewhere along your route before arriving) and pick up snacks to keep in your hotel room for the kids.