Benitez stated that he waited to shake Ferguson's hand at the end of their FA Cup clash at Old Trafford last weekend, but his opposite number didn't appear.
However, the Scot has insisted that the former Liverpool boss is talking "nonsense", and that he was signing autographs after the full-time whistle.
Ferguson told reporters: "It is nonsense. Why would I refuse to shake his hand?
"I was signing autographs and I never saw him. Why he has said that I have no idea. If he wanted to shake hands he could have stood straight in front of me. It is absolute nonsense."
The game between the two clubs ended in a 2-2 draw.