The couple issued a statement Saturday in a short video posted on social media.
Kutcher and Kunis took to Instagram on Saturday and posted a video and apologized, saying it was never their intent to undermine the testimony of the victims or re-traumatize them in any way with the letters they submitted to Los Angeles Superior Court Judge Charlaine F. Olmedo.
"We are aware of the pain that has been caused by the character letters on behalf of Danny Masterson," Kutcher said in the video, to which Kunis followed with, "We support victims. We have done this historically through our work and will continue to do so in the future."
Kutcher then explained that a couple of months ago, Masterson's family reached out to them and asked if they would write character letters on behalf of Masterson "to represent the person that we knew for 25 years" so that "the judge could take that into full consideration relative to the sentencing."
"The letters were not written to question the legitimacy of the judicial system or the validity of the jury’s ruling," added Kunis, who starred alongside Kutcher and Masterson on That '70s Show.
"They were intended for the judge to read and not to undermine the testimony of the victims or re-traumatize them in any way," Kutcher continued. "We would never wanna do that. And we’re sorry if that has taken place."
In closing, Kunis said, "Our heart goes out to every single person who’s ever been a victim of sexual assault, sexual abuse or rape."
The couple's statement comes one day after ET reported that they were among the 50 people who submitted letters to the judge in hopes of persuading her to show mercy to the disgraced actor. The couple -- who portrayed Michael Kelso and Jackie Burkhart in the hit Fox sitcom -- leaned on their long history and friendship with Masterson, whom the couple referred to as "a role model" with "exceptional character."
Actors Debra Jo Rupp and Kurtwood Smith -- who famously portrayed Kitty and Red Forman on the show -- also wrote letters to the judge, as did actors Giovanni Ribisi and William Baldwin, whose wife, Chynna Phillips, is the sister of Masterson's wife, Bijou Phillips.
Kunis and Kutcher's apology also came one day after Ashley Hinshaw -- the wife of That '70s Show star Topher Grace, who played Eric Forman -- spoke out on Instagram following Masterson's sentencing.
Hinshaw said, "To every rape victim that is [re-traumatized] by witnessing society debate and focus their attention on what is going to happen to the RAPIST...I see you."