DeGrom, 33, flew to Los Angeles earlier in the week to have an MRI read by doctors. It showed some progress in his recovery but not enough to start pitching again.
"It's slightly improving, but it's going to be two more weeks, no throwing," Rojas said in a Zoom session with reporters. "Then we'll see further imaging after two weeks."
DeGrom has been out more than a month already as the Mets have fallen out of first place in the National League East without him on the mound. He is 7-2 with a 1.08 ERA and has endured starts and stops to his season, leaving several games early due to arm troubles.
"He's frustrated," Rojas said. "He wants to pitch. He wants to help the team. There's nothing he can do. Just have to commit to these two weeks."
DeGrom informed his teammates of his status after his return from Los Angeles.
"Even after hearing this news, I don't think that's going to put these guys' heads down," Rojas said.
Rojas said they haven't charted a plan for deGrom if the Mets make it to the postseason.
"We haven't talked past the two weeks about any of that," Rojas said. "We're going to trust that these two weeks are going to do well for him."