Rivera says Gettis, who started 15 games for the Panthers in 2010, will not play for Carolina in its preseason home opener Saturday night against the Houston Texans.
For now, Gettis remains on the active-PUP list.
Gettis tore his left ACL last year in training camp and has been rehabbing ever since.
He's expected to compete with Louis Murphy, Seyi Ajirotutu and Kealoha Pilares for the No. 3 receiver spot when he returns. Steve Smith and Brandon LaFell are the team's projected starting receivers.