In injury-time, Bradley went down with what appeared a major knee injury. However, with the Reds fullback on the pitch and Arsenal chasing a winner, Martinelli first kicked the ball at Bradley before making an attempt to drag him off the pitch.
Martinelli's actions enraged Liverpool's players, with the reaction seeing Ibrahima Konate shown a yellow card.
After the match, Martinelli took to Instagram to explain his actions and deliver an update.
He posted: "Conor and I have messaged and I've already apologised to him. I really didn't understand he was seriously injured in heat of the moment.
"I want to say I'm deeply sorry for reacting. Sending Conor all my best again for a quick recovery."
Martinelli a nice guy
Post-match, Liverpool manager Arne Slot said of the incident: “I don’t know Gabriel Martinelli but he comes across as a nice guy.
"I think the problem for him is, and it’s a problem in general in football, that there is so much time-wasting and players pretending they are injured in the final parts of the game, that you can then sometimes be annoyed if you want to score a goal that you think the player is time-wasting.
“I cannot ask of Gabriel Martinelli in the 94th minute when it’s so emotional for him to understand he is playing Liverpool – a team when we played Leeds and a player was held but didn’t go to the floor, or played West Ham United and my players try to drag Paqueta out of a situation where he was getting a second yellow card.
“I’m 100% sure that if he knew what the injury might be that he would never do (what he did). But it doesn’t look great if he (Bradley) has the injury which we fear he might have.
“But time-wasting and diving in football has come to the situation where players think in the 94th minute that it’s happening again, because I’ve seen it happen against us so many times this season.
“I can understand Martinelli might have thought this was time-wasting and didn’t think this was Liverpool.”