The director and now-co-chief of all things DC shot down a rumor that started to pick up steam these past couple days ... namely, the notion that George could possibly come back and reprise his role as Batman in the new 'Batman' movie that was recently announced.

On Saturday, Gunn responded to a fan who flat out asked him if it was true he was going to cast GC in the 'Brave and the Bold' flick ... which features a much older Batman (and his son, Robin).

When someone pressed for further details -- asking if there was any truth to the idea he was going to cast an actor who'd previously played Batman, period -- Gunn again flatly denied that ... saying they were going in a completely new direction with a totally new actor.

The reason this began percolating at all is because a film journo claimed to have the inside scoop on DC's hopes when it came to who they wanted under the cowl in their latest reboot of the franchise ... suggesting it was either Clooney, Val Kilmer or Christian Bale, and that this person may even cameo in the new 'Flash' flick that's coming out this year.

She said she knew who the studio wanted -- noting a deal wasn't in place yet -- but refused to identify the alleged favorite in mind ... and Twitter handled the rest, making all 3 trend.

Considering plans for this new Bat-movie were literally just unveiled about a week ago, it's safe to say ... no one is cast until they're cast -- so it's probably best to just wait until this actually goes into production before diving head-first into conjecture.