Using interfaces and Monobehaviour behaviours

Hi there, I've been trying to utilise interfaces in order to create clean code. I have an interface, IAttackBehaviour that has one void of Attack(), which a character has reference to to invoke it's attack function. Like:

 IAttackBehaviour atkBehaviour

 void Start()
 {
 atkBehaviour = new RockThrow()
 }

 void Update()
 {
     if(input.GetKeyDown("space"))
     {
     atkBehaviour.Attack();
     }
 }

Where one IAttackBehaviour subclass is a RockThrow class that will instantiate a rock projectile as it's Attack() function, but because interfaces don't inherit monobehaviour, I'm unable to do this directly from the RockThrow class, I was wondering what a good solution would be?

Thank you.