Is there an expression for directing your opinion to someone but you use someone else's name?

Imagine there are 3 people A, B, and C. A and B are talking, A says to B that person C thinks he is arrogant. But actually, that’s what person A is thinking. He just uses person C to avoid possible side effects or to make his opinion more valuable. The important thing is that person A does not have bad intention. Is there an expression in English that would explain what person A is doing?