1. Show both positive feedback as well as negative reviews with your crew and management to boost employee morale and make corrections to your food, service and operation.
2. Carefully respond to positive and/or negative reviews, and when answering to negative reviews, respond privately rather than widely. This helps avoiding an online "battle" where you're the center of attention.
3. Another idea is to invite negative critics back in for a courtesy visit if it was their first experience at the restaurant. Or offer them a discount to come back. Then, follow up with them after the visit.
4. You can contact Yelp or the user review company if you been the victim of spam, fraud or false reviews posted by a disgruntled employee. Sometimes reviews will be posted by fake users.