The apology was made in a joint statement by the CFL Players' Association and B'nai Brith Canada.
"I wholeheartedly apologize to all those who I know I let down by posting those videos, especially those who look up to me as a professional athlete," Mitchell said. "I fell into a trap by watching that video and I hope others can learn from my very public mistake.
"This is a learning moment for me."
Mitchell agreed to work with B'nai Brith, a Jewish human rights organization, to "educate myself about this and other human rights matters."
The Virginia Beach, Va., native had talks with B'nai Brith chief executive officer Michael Mostyn as well as with the CFL, the CFLPA and the Alouettes after news broke Thursday of a series of posts on Twitter dealing with Israel, including one with a link to a video called "The Greatest Lie Ever Told, the Holocaust."
"I have come to see that he is a very genuine individual who truly did not comprehend the deceptive nature of this vile video," said Mostyn.
CFLPA president Scott Flory added: "We hope that people will accept his apology and we support him on his journey to become a positive force."
Mitchell was fined undisclosed amounts by the CFL and the Alouettes for violating the league's social media policy. Flory said the league fine will be donated to a charity of the player's choice.
The six-foot-six lineman signed with Montreal last season from the B.C. Lions. He was a CFL all-star in 2011.