Unfortunatly there are no direct buses from Novigrad to the National park Plitvice lakes, easist way to get there is to join a bus excursion pffered from Novigrad. To reach the park with public bus, you have to travel from Novigrad to Karlovac or from Novigrad to Rijeka and then Rijeka to Karlovac, from Karlovac there is buses to Plitvice lakes