The Spaniard said Friday he would bypass next week's Queen's Club tournament after being advised by doctors to rest. He is the defending Queen's Club champion.
He is expected to be ready to play at Wimbledon, where he is also the defending champion. This year's Wimbledon Championships begin June 22.
"I have been having some problems in the past months with my knees, that's no secret, that did not allow me to compete always at 100 percent," Nadal said in a release.
"I need to work with my team to recover well, work on my physical condition to be at my top form and get ready for the grass to play at Wimbledon. I hope I can be ready to compete by then. I am really sorry and I hope that the people at the tournament will still want me to come next year."
Nadal's string of four consecutive French Open titles was ended in a fourth-round loss Sunday to Sweden's Robin Soderling in Paris.