The moles are feeding on the grubs, earthworms and other soil critters beneath your tomatoes—not the roots. The moles’ digging does sometimes damage the plants, but they usually recover if you press their roots back into good contact with moist soil.
A repellent mixture of castor oil and soap usually causes moles to leave an area. Put one-half cup each of castor oil and dishwashing liquid in a jar, and shake well. Use this as a concentrate and mix 2 to 3 tablespoons in a gallon of warm water. Use a watering can to dribble it over the area you want to protect. A castor oil-based commercial product called Mole-Med can save you some of the mixing. Until you get the animals to feed somewhere else, make time to visit your garden each morning and step on all the tunnels around your plants.