Linkin Park's new lead singer is responding to fan backlash about her connection to actor Danny Masterson ... apologizing for her association and saying she misjudged the guy.

Here's the deal ... LP announced Emily Armstrong -- cofounder of the group Dead Sara -- as their new lead singer, about seven years after beloved vocalist Chester Bennington's death.

Within hours of the announcement, fans started pointing out Emily attended a 2020 preliminary hearing in support of Masterson -- who last year was convicted on two counts of forcible rape -- especially upsetting to them since Chester talked openly about surviving sexual abuse.

EA didn't name-drop Masterson, but she did release a statement that seems to reference the disgraced actor ... saying years ago she was asked to support someone she considered a friend during a hearing.

Emily says, after attending the hearing, she realized she shouldn't have ... adding she always tries to see the good in people, but she misjudged this person.

She says she hasn't spoken to him since ... and notes she doesn't condone violence against women and she empathizes with the victims of this person's actions.

Again, no mention of Masterson by name ... but, people are putting two and two together. That said, the statement's not fully getting Armstrong out of hot water -- 'cause fans are still side-eyeing her for her alleged association with Scientology.

She attended galas at the Church of Scientology with her former bandmate, Cedric Bixler-Zavala ... whose wife, Chrissie Carnell Bixler, accused Masterson of abuse as well.

Linkin Park's standing by Emily BTW ... with no announcement that they're kicking her out of the group. They've got a new album coming out in November and an international tour kicking off next week.