Greta Gerwig Says Her Next Project Is Already Giving Her Nightmares

Greta Gerwig is already circling her next movie -- but it ain't gonna be a walk in the park the way "Barbie" has been ... if anything, she makes it sound like the exact opposite.

The writer-director made an appearance Sunday at the London Film Festival -- where she went onstage for a sitdown interview with "Succession" creator Jesse Armstrong ... who asked her a bunch of questions, including what she had coming down the pike.

Gerwig didn't get into specifics about what exactly she was working on ... but confirmed she's already in the writing process for another feature, over which she's feeling apprehensive.

She says, "It’s hard and I’m having recurring nightmares." There's no video that's surfaced of her making this comment -- only recaps from outlets that were present -- so there's no real context as to the exact emphasis she placed on this, or what she even really means.

Some have characterized her remarks as feeling dread over re-entering the writing process ... but the quote on its own is a little strange, considering "Barbie" was light-hearted and easy viewing -- not to mention a complete home run crowd pleaser.

What we can surmise is that "Barbie 2" isn't what she's talking about. There's been no word on a green-lit sequel yet -- despite the OG's success -- any inkling of that would've leaked out by now if it was already happening. Then again, the WGA strike did just end -- so ... 🤷🏽‍♂️