The front page of Monday's Sun newspaper carried a picture of Defoe seeming to bite the Argentine's upper arm as they sat on the ground following a challenge at White Hart Lane.
Mascherano was booked for his tackle from behind and Defoe for his response, the incident producing a mass bout of shoving in the game which Spurs won 1-0.
Tottenham coach Martin Jol played down the incident, saying that Defoe, a former West Ham player, told him he was "nibbling his arm."
"There will be no mark. Ask Mascherano if he has got a mark," the Dutchman said.
"It is part of the game. They kicked him (Defoe) three times from behind in 10 minutes and he wanted to show his frustration in a nice, comical way."