He said: “Before you know it, my barber had taken his phone out and had gone up to the window and started recording.
“I then saw the guy outside swing for the police officer and throw him down on to the ground.
“I thought, ‘I’m not sitting back and watching this’.”
Mr Whiting said he was thinking of his sister and felt it was about “putting yourselves in other people’s shoes”.
“If that was my sister, I would hope somebody wouldn’t hesitate to help her if she was on her own,” he said.
“So before you know it, I’ve run out of the door.”