The actress reunited with her former costars Sunday night at the Motion Picture and Television Fund's 17th Annual Evening Before Gala ... and Jenna Ortega was standing right by her, literally and figuratively.

Remember, Melissa was fired back in November from the 7th installment of the horror franchise over her Israel-Palestine posts.

Jenna appeared to like a post on Melissa doubling down on her pro-Palestine stance at the time of her firing ... and she too dropped out of the new 'Scream' movie -- though it was apparently due to a schedule clash with Netflix's "Wednesday" and not cause of MB's firing.

But Jenna's support was loud and clear in the new IG snaps shared by Melissa ... where she was also joined by her other  'Scream' costars Mason Gooding, Jasmin Savoy Brown, Liana Liberato, Tony Revolori, Skeet Ulrich, and Jack Quaid -- who all appeared to have her back, too.

As we reported ... Melissa doubled down on her pro-Palestine stance over Xmas while the 'Scream' Empire collapsed with director Christopher Landon also walking away from the new movie.

While Spyglass lost their 2 big leads and their director ... Neve Campbell recently teased a possible return to the franchise as Sidney Prescott -- only for the right amount of money, though.

She initially left the franchise due to pay disagreements, so that doesn't come as a shock -- but she ain't biting the hand that feeds her ... saying at Saturday's BAFTA Tea Party in L.A. she was sad the higher-ups at 'Scream' were struggling.