Arsene Wenger's men led 1-0 when Coquelin was given a second yellow card for a late tackle on Harry Kane, and seven minutes later they found themselves 2-1 down.
Alexis Sanchez rescued a draw, but Arsenal are now eight points behind Premier League leaders Leicester City with just nine matches remaining.
“I'm really sorry to all the fans for the red card, I think with 11 against 11 we could have won the game as we were playing really well,” Frenchman Coquelin told Arsenal TV.
“This red card changed the game. I'm really sorry to the club, to the team and all the fans. I actually thought I could get the ball when I slide tackled (Kane) -- that is why I went for it. I touched him and (the referee) gave me the second yellow.
“I didn't really see the goal [because I was in the dressing room] but someone came and told me that we scored the second one -- it was a relief for me.
“I did not want us to lose today because at 1-0 I thought we were doing great. But at the end of the day, it's a good point and hopefully it will be an important point for the title.” – AFP
Original source: Coquelin apologises for red card