Will Smith Demands Sexual Harassment Lawsuit Be Dismissed

12:18 PM PT -- Brian King Joseph's lawyer tells TMZ ... "A jury’s ultimate determination matters more to us than Mr. Smith’s opinion of this case."

Will Smith is asking a judge to throw out the sexual harassment lawsuit against him ... with his lawyer alleging that the filing is just a desperate attempt to shake the star down for cash.

Remember ... violinist Brian King Joseph filed a lawsuit against Smith last month, in which he claimed he returned to his hotel room in Las Vegas and found a note reading, "Brian, I’ll be back...just us,” which was signed by “Stone F."

He also said that he found "wipes, a beer bottle, a red backpack, a bottle of HIV medication with another individual’s name, an earring, and hospital discharge paperwork belonging to a person unbeknownst to Plaintiff.”

In the motion to strike, Smith's team argues Joseph admits he doesn't know who "Stone F" could be ... but, he's inexplicably filed a suit against Smith and his company, Treyball Studios.

In addition, though Joseph claims he was invited to join the tour, Smith says he was hired only on a per-show basis and wasn't promised a position in the band.

Joseph and Smith were never alone together, the filing states ... so, Smith's lawyers say it's unclear what Joseph meant when he said he was allegedly "grooming" him.

Smith's team is hoping the judge will grant their motion to strike ... but, they also state in the lawsuit they're ready to provide witnesses who will explain Joseph wasn't invited to continue on with the group because he "behaved erratically, was difficult to work with, and made the other members of Mr. Smith's band feel uncomfortable."

Ultimately, Smith's side claims this is a "frivolous lawsuit" and an "attempted money grab."