Nadal, a 14-time Roland Garros champion, skipped the ongoing Madrid Open and has also missed tournaments at Indian Wells, Miami, Monte Carlo and Barcelona.
"I'm very sorry to announce that I will not be able to be in Rome," the Spaniard said in a statement on social media.
"You all know how much it hurts to miss another one of the tournaments that have marked my professional and personal career for all the love and support of the Italian tifosi.
"Despite having noticed an improvement in recent days, there have been many months without having been able to train at a high level and the readaptation process has its times and I have no choice but to accept them and continue working."
Nadal has competed at Roland Garros every year since winning the first of his men's record 22 major titles in Paris in 2005. The French Open begins on May 28th.
