Cook the pasta according to package instructions. Drain and let cool.

In a large mixing bowl, combine the cooled pasta, drained tuna, cherry tomatoes, cucumber, red onion, and bell pepper.

In a small bowl, whisk together olive oil, lemon juice, dijon mustard, salt, and black pepper.

Pour the dressing over the pasta mixture and toss to combine. Add chopped parsley and mix well.

Serve chilled or at room temperature.