In a statement issued through the team, Shanahan said:
"I was frustrated, and in the process of trying to get some answers from the officials, I conducted myself in the wrong way. I ask our plays to hold themselves to a high standard and be accountable and I know that I'm accountable for my actions as well.
Shanahan, the son of head coach Mike Shanahan, was given an unsportsmanlike conduct penalty in the closing moments of the Redskins' 38-31 loss to the Bengals and was in a heated argument with the officials. Shanahan was seen after the game running to catch up with one of the officials as he continued to yell and argue.
The NFL will be reviewing Shanahan's conduct to determine if he will be fined or suspended for his conduct.