Ibanez, who has been on the 15-day disabled list since June 18 with a strained left groin, had been scheduled to begin a rehab assignment Wednesday with Double-A Reading. But that got pushed back to Thursday.
Thursday then got pushed back to Friday, which means he will not play against the Mets this weekend at Citizens Bank Park.
"We're just trying to make sure that he doesn't get on the field unless he feels 100 percent," Phillies general manager Ruben Amaro Jr. said. "He has improved. He hasn't had a setback. It's just a matter of him not being quite ready to get on the field and play at his accustomed level yet. When he's ready to do that, whether it's today or [Friday] or in five days, we have to make sure that he's comfortable and he is not having any feeling or symptoms of the injury.
"He's doing really well. He's basically done all the drills. But until he feels comfortable -- and the doctor and the trainer feels comfortable -- there's no reason to do it and risk further injury."
Left-hander Scott Eyre made a rehab start Wednesday with Reading. He allowed three hits, one run, one walk and one home run in two-thirds of an inning. He has been on the DL since June 12 with a strained left calf.
"He was rusty," Amaro said. "Physically, he was fine."
Amaro said Eyre is scheduled to pitch Friday night and the Phillies will see where he is after that.
Right-hander Clay Condrey has been on the DL since June 19 with a strained left oblique. Amaro said Condrey has been improving. Amaro said Condrey has been throwing and feeling much better.
Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.