Bring a large pot of lightly salted water to a boil. Cook orzo in the boiling water, stirring occasionally until cooked through but firm to the bite, about 11 minutes. Drain.
Mix orzo pasta, tomatoes, and olives together in a large bowl. Pour pesto over pasta mixture and stir to coat. Sprinkle Parmesan cheese over the pasta mixture; stir. Drizzle olive oil over the salad and stir to achieve your preferred moisture level.