"Knowing that they are unable to deliver their signature high energy show, Sum 41 made the tough decision that a break is needed while Deryck begins rehabilitation for the slipped disc," the group said in a statement Wednesday.
The rocker's condition has not improved but he "is expected to make a full recovery with the necessary treatment and rest," says the band.
According to reports, three men attacked Whibley in a bar last week in Japan, where Sum 41 had been playing the Summer Sonic rock festival. The incident aggravated a previous disc injury from 2007.
"[We] are very disappointed that we have to pull off the tour. [But] we know that it would be more frustrating for the fans if we can't give it our all," says drummer Steve Jocz. "Deryck is doing everything he can to get himself better and we're there for him."
The band hopes to be back on the road again in Europe at the end of August.
Reporting by MARISA LAUDADIO