you’re working on something else than the person trying to interrupt you.
Don’t like to get interrupted? Perhaps you should’ve worked together on the same thing instead.
Reduce the number of interruptions by reducing the number of things you, as a team, are working on at the same time, not by making yourself less available.
Interruptions are not the cause of the problem, but the effect of having too many things in flight (i.e. high WIP).