Usher says he needs to take things nice and slow, so he’s postponing more shows … explaining he’s dealing with a painful neck injury.

The R&B star just announced he suffered an injury to his neck earlier this week during a rehearsal for his “Past Present Future” tour.

Usher says he was hoping physical therapy and medical treatments would be enough to get him back on stage ASAP, but he says the injury isn’t healing fast enough and his doctors are instructing him not to perform.

He was supposed to kick off his tour Wednesday, but a few hours before the show was set to begin he announced he was pulling the plug … saying he needed to let his body rest and heal.

The singer didn’t disclose the neck injury until Thursday … he says he needs to be 100% so he can give fans the “excellence you expect from an Usher show.”