"I have been to the hospital yesterday for a check up and the analysis was that I am currently suffering from a strain injury," she said on her Web site.
"I've been advised to rest and am therefore forced
"I would otherwise jeopardize my participation in Antwerp and I certainly want to avoid that," said the 23-year-old.
Clijsters, who has said she will quit this year, lost in the Australian Open semi-final to Maria Sharapova.
The Diamond Games in Antwerp will be Clijsters' final tournament in Belgium.