Cook the rotini pasta according to package instructions until al dente.
Drain and rinse the pasta under cold water.
In a large bowl, combine the cooked pasta, cherry tomatoes, cucumber, olives, and bell pepper.
In a separate bowl, mix the mayonnaise, Greek yogurt, and Dijon mustard.
Pour the dressing over the pasta and vegetables.
Toss everything together gently until well coated.
Add salt and pepper to taste.
Chill the pasta salad in the refrigerator for at least 30 minutes.
Before serving, stir and garnish with fresh parsley.
Serve chilled or at room temperature.