"To keep it real, the Shogun fight will have to wait. I just found out that I have to get surgery on both knees," Jackson said Thursday on Twitter. "But I heal fast; don't trip."
Jackson did not say when he is scheduled to have the surgery.
UFC announced the fight between two of its former light heavyweight champions Tuesday night while also revealing Jackson would no longer be part of the promotion after the bout. Jackson has only one more fight on his UFC contract.
UFC has yet to determine a date for the Jackson-Rua fight.
When Jackson is healthy enough to return, he will face Rua for the second time. The two first met in April 2005 during a Pride Middleweight (205 pounds) Grand Prix bout.
Rua defeated Jackson by first-round TKO in Osaka, Japan.