Meanwhile, Del Toro remains confident the project will come together in due course.
"As far as I'm concerned, Pacific Rim 2 is not cancelled, just postponed," he told Variety.com.
"Right now, we have to put a budget and screenplay together, present it to Universal and Legendary, and they will make a decision (on a new release date)."
Pacific Rim 2 has been replaced on Universal's release schedule by another sequel, musical comedy Pitch Perfect 3, bumping it up from its previous September, 2017 date.
News of the delay emerges three months after Del Toro passed on the chance to direct his passion project Justice League Dark in June to focus on Pacific Rim 2.
"Warners liked the script, they were very enthusiastic and wanted to green-light it but they wanted it to coincide with the shoot of Pacific Rim 2," he told TheDailyBeast.com.
"I was put in a very difficult place facing a difficult choice, and I chose to do Pacific Rim 2."
Warner Bros officials have yet to name a replacement director for Justice League Dark, which is separate from Zack Snyder's Justice League franchise.
His upcoming movie will feature Man of Steel's Henry Cavill as Superman, Ben Affleck as Batman, Gal Gadot as Wonder Woman and Jason Momoa as Aquaman.
- WENN