Rinse the calamari under cold water and slice them into thin rounds.
In a large skillet over medium heat, sauté the onion in the olive oil and allow to turn golden. Add the calamari and cook for a couple of minutes. Add the white wine and let evaporate. Add the tomatoes, salt and pepper. Cook for about 20-30 minutes until reduced.
Meanwhile, bring a large pot of salted water to a boil. Cook the pasta until al dente, drain it, and add it to the pan with the calamari. Mix together for about a minute. Serve immediately with a garnish of fresh parsley.