Drain and rinse cannellini beans and set aside. Sauté celery, onions, garlic, carrot and zucchini in olive oil for about 10 minutes. Stir in broth and tomatoes and bring to a boil. Reduce heat and simmer partially covered, for 20 minutes. Add beans, pesto, salt and pepper. Simmer for about 5-10 minutes. Ladle soup into bowls and garnish with grated parmesan cheese.