The world number two pulled out a day after a surprise round-of-16 defeat to 35th-ranked Alexandra Eala at the Berlin Open.
“Unfortunately, I have to withdraw from Bad Homburg due to some discomfort in my right hip," Rybakina, 27, said in a story shared by the tournament's official Instagram page.
"I need to consult with my medical team and undergo further assessment before making any decisions about the next steps. Thank you for your understanding and support.”
The 2022 Wimbledon champion has now lost three of her last four matches, a run that began with a second-round defeat to Yuliia Starodubtseva at the French Open.
On grass, she won her opening match at Queen’s Club before losing to Katie Boulter in the quarter-finals, and then fell 7-5 6-4 to Eala in Berlin on Thursday.
Rybakina is 32-10 this season, having won titles at the Australian Open and Stuttgart, but will now focus on regaining fitness ahead of Wimbledon, which begins on June 29, as she bids for a second title at the All England Club.