The three-time champion jockey, 32, has not put a timescale on his return to the saddle.
"I'm not going to rush it," he said. "I want to be 100% for all the major races in the autumn."
Moore looks set to miss York's four-day Ebor Festival, one of the biggest fixtures on the flat-racing calendar, which begins on 17 August.
The major autumn races include the Prix de l'Arc de Triomphe, British Champions Day, the Breeders' Cup and the Melbourne Cup.
The lay-off will damage his chances of winning the jockeys' championship for a fourth time.
Moore, the number one rider for Irish trainer Aidan O'Brien, is second with 57 winners this year, two behind Silvestre de Sousa.
He finished as top rider at the recent Goodwood Festival with eight victories.
"I have been a bit sore for the last couple of weeks and been advised by a specialist that complete rest is the best option," he added.
"I'm going to play it by ear, but hope to be back soon."
Moore was sidelined for two months last year with a neck injury.
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Leading flat jockey Ryan Moore has been advised to take "complete rest" as he recovers from a hip injury.