Rebecca Ferguson Says Costars Freaked Out After Screaming A-Lister Story

Rebecca Ferguson's story scared the heck out of some former costars ... leading A-listers to call her in an accusatory way -- but, she says she's not worried about it.

The actress -- who confessed a mystery costar tore into her on set -- opened up about the moment during an interview on "The Jess Cagle Show" ... saying she didn't think about the huge reaction her tale might get.

Ferguson says she didn't necessarily want internet sleuths to try and find the A-lister she says screamed in her face back in the day ... she just wanted to answer the question.

And, Ferguson says social media users weren't the only people to flip out at her story ... explaining she received calls from some amazing costars worried people might think they bit RF's head off in days past.

Ferguson says the callers demanded to know if she'd realized what she'd done ... putting their names out there as possible suspects for the screwed-up behavior.

Rebecca says she didn't want to put anyone's name in the rumor mill -- though she says it's not her job to protect other celebs when she's telling her life story.

Remember ... Ferguson set the internet ablaze in February when she revealed a costar -- whose name and gender she made sure to hide -- would scream right in her face and insult her during filming.

She says she finally stood up for herself after no one on set stepped in ... telling the actor to back off before demanding he/she face away from her during scenes together.

Seems like tons of actors were terrified about their public image ... even if Ferguson didn't intend to cause any drama -- but, she's cleary not concerned either way.