The Argentine midfielder was dismissed just before half-time in Sunday's 3-0 defeat at Old Trafford for a second yellow card.
. Mascherano has now expressed his disbelief at Bennett's decision and insists he did not swear at the official in the incident which saw him dismissed.
"I do not know why I was sent off," Mascherano told the Liverpool Echo.
"I asked the referee what was happening. I did not swear, I was not aggressive and I did not confront him.
"All I did was ask him what was happening, nothing else.
"So when he showed me the second yellow card and sent me off I could not believe it.
"I am sorry to my team-mates because that meant we went down to 10 men and that made things even more difficult for us."
