11:00 AM PT -- Savage says Hwang's accusations are without merit and absolutely untrue, and claims they were investigated, but ... "None of her claims could be substantiated because they did not happen."

Savage says he's worked in entertainment his whole life and has "always endeavored to treat everyone on any set I work on respectfully and professionally." He adds ... he supports all people who feel they are being mistreated to come forward and speak out, but he also must "protect myself and my family from those seeking to tarnish my good name."

Fred Savage is getting sued for allegedly assaulting a costumer on his TV show "The Grinder" -- but she also claims he regularly tormented female crew members, demanding they don't make eye contact with him.

In the suit, filed Wednesday in L.A., Youngjoo Hwang says Savage constantly gave her dirty looks, rolled his eyes and hurled profanities at her while they were working on the show in 2015. Hwang says Savage made no secret of the fact he didn't like her, saying things like, "It's so f**king annoying that I have to be nice to you when I f**king hate you!"

According to the docs, obtained by TMZ, Savage had a rep for intimidating and tormenting female crew members, demanding they stop following him around -- even though it was their job to do so -- and told them, "Don't ever even f**king look at me anymore!"

TMZ broke the story ... Hwang claims Savage eventually blew up at her when she dusted dandruff off his tuxedo jacket, as part of her job. In the suit, she says he yelled, "Do not touch me with your hands" -- and when she explained what she was doing he "violently struck [her] arm three times with his hand."

Hwang says she reported this, but was told by an executive producer, "I'm not even sure what Fred did constituted harassment and I don't think you should report it to H.R."

She claims FOX protected its star, and did nothing to clean up the hostile work environment Savage created. As we told you, a source close to Fred says FOX actually did investigate Hwang's allegation and found zero evidence to back her story.