Strathclyde Police have confirmed they have received a complaint relating to a gesture made by Celtic boss Neil Lennon at the end of Sunday's Old Firm derby.
However, they indicated they would not be following it up as officers in attendance witnessed Lennon's gesture - which involved the Northern Irishman cupping his ears as he left the field - and did not take any action at the time.
A spokeswoman for the police said: "We can confirm we have received a complaint regarding Neil Lennon at the end of the Rangers-Celtic football match.
"Strathclyde Police officers were in attendance at the time and would have taken action at that time if they had deemed it appropriate."
Celtic chief executive Peter Lawwell said: "It is absolute nonsense. It is laughable that such a ludicrous complaint has been made given the abuse Neil received throughout the match.
"It tells you more about those making the complaint than it does about Neil."
When the gesture was mentioned after the game, Lennon said: "Don't ask me about that. It's called humour, all right?
"Don't distract away from my team's performance. Don't even write about it. You have the photographs, I'm sure, but it is just a bit of fun. I don't want to distract from my team's performance today."
Nine people were arrested at the game but none of the crimes was linked to sectarianism, police said. Six arrests were made in the ground, with another three immediately outside.
A spokesperson for Strathclyde Police added that all arrests were for "minor offences" such as being drunk inside the stadium and breach of the peace.
Police had predicted a surge in violence over the weekend and an extra 1,000 officers were deployed to the streets. The heightened tension had come about after it was revealed parcel bombs had been sent to Lennon.
On Saturday, two men were arrested following police raids targeting the homes of people allegedly involved in Old Firm internet hate campaigns.
A 23-year-old and a 27-year-old were charged with sectarian breach of the peace and are expected to appear in court on Tuesday.
The operation targeted individuals posting racial and religious hate comments about Lennon and Rangers striker El-Hadji Diouf, police told the Daily Record newspaper on Friday.