Are you talking about business phone calls or personal home phone calls? If it is a business call, you could simply say that the person is “unavailable” and offer voice mail or to take a message. That’s standard business procedure and is a perfectly legitimate means of protecting colleagues from having their work interrupted.
If it is a personal home call that procedure is also okay, but I would be reluctant to act as a “buffer” between the caller and the person who is standing next to you refusing to talk to the caller. Unless there is some reason to do otherwise, I’d hand the phone to its intended recipient and insist that he deliver his own message that he is unable to talk to the caller.
