Following his side's 2-1 defeat, Tigers chief, Phil Brown claimed in his post-match press conference that Fabregas - who had not taken part in the FA Cup sixth-round tie at the Emirates Stadium due to injury - had spat at his assistant manager in the tunnel area at the end of the game.
The Gunners' skipper strenuously denied the accusations, while manager Arsene Wenger claimed he did not see anything.
However, former Manchester City and Port Vale boss Horton has now contacted the LMA over the incident.
"The LMA can confirm that Brian Horton has made contact regarding incidents surrounding Hull City's sixth-round FA Cup match against Arsenal at Emirates Stadium on Tuesday night," read a statement.
"As the incidents fall firmly within the jurisdiction of the Football Association, which is making its investigations in the prescribed manner, neither the LMA nor Brian Horton will be making any further comment at this time."
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