In a large pot of boiling salted water, cook the fettuccine or spaghetti according to package instructions until al dente. Drain and reserve 1/2 cup of pasta water.
In a mixing bowl, combine the sour cream, cream cheese, lime juice, minced garlic, lime zest, and olive oil. Mix until smooth and creamy.
In the same pot you used for the pasta, combine the drained pasta with the creamy sauce. Stir well to coat the pasta evenly. If the sauce is too thick, slowly add some reserved pasta water to reach your desired consistency.
Fold in the chopped cilantro into the pasta mixture and season with salt and pepper to taste.
Transfer the creamy cilantro lime pasta to serving plates. If desired, sprinkle with grated Parmesan cheese and garnish with halved cherry tomatoes for a pop of color.