Deadman was accused by Shrimpers fans of raising two fingers in their direction while appearing to rub the back of his head during the goalless draw at Fleetwood in npower League Two last Saturday.
The alleged incident at the Highbury Stadium came midway through the first half while the match official was standing over striker Britt Assombalonga as he received treatment from the club's physio.
But an FA statement read: "Following an allegation that referee Darren Deadman made an offensive gesture at supporters during the League Two match between Fleetwood Town and Southend United on December 8 2012, The FA reviewed video footage and was satisfied that there was insufficient evidence to support the claim.
"Therefore, The FA can confirm that no action is required."
- Sports & Recreation