The Arsenal winger said he was "deeply sorry" for his actions in the closing stages of the 0-0 match and confirmed that he had apologised directly to Bradley.
The incident occurred as tensions rose late on, with Martinelli throwing the ball at the 22-year-old before shoving him off the pitch. Bradley was then manhandled by Martinelli while lying on the turf, prompting furious reactions from Liverpool players.
Bradley, who was seriously injured in the incident, later left the stadium on crutches and was seen wearing a supportive brace on his left knee. Martinelli was shown a yellow card by the referee, a decision that did little to calm the fallout after the final whistle.
The clash sparked strong criticism from former Manchester United captain Roy Keane, who labelled Martinelli "a disgrace" while speaking on Sky Sports. Keane questioned the intent behind the Arsenal player's actions and suggested stronger punishment should have followed.
"Conor and I have messaged and I have already apologised to him," Martinelli stated via Instagram.
"I really didn't understand he was seriously injured in the heat of the moment. I want to say I'm deeply sorry for reacting. Sending Conor all my best again for a quick recovery."
Arsenal manager Mikel Arteta, however, defended Martinelli in his post-match comments, insisting there was no malicious intent and describing the episode as an emotional reaction in a tense moment.
"Knowing Gabi, he's an incredible, lovely guy, and he probably didn't realise what happened," said Arteta.
"I hope that Conor is well, I will have a word with him to understand that. Probably (Martinelli) didn't recognise what happened."
Arne Slot repeatedly turned to his own words to explain Liverpool's frustration and concern after Conor Bradley was injured late on in the 0-0 Premier League draw with Arsenal on Thursday night.
Mikel Arteta said his Arsenal side deserved major credit for a "remarkable" festive run after a goalless draw with Liverpool that still left the Gunners six points clear at the top of the Premier League.
Mikel Arteta has said Arsenal "have a point to prove" as they prepare to host defending Premier League champions Liverpool at the Emirates Stadium tonight.
Arne Slot has hit back strongly at claims Liverpool have become "boring", insisting his team remain committed to attacking football as they prepare to face Premier League leaders Arsenal tonight.
