Ribery's comments deepened a battle between the French camp and Bayern Munich on the eve of the country's opening World Cup Group E match against Honduras.
"It's not good," Ribery said of the cortisone steroid injection that French team doctor Franck Le Gall had wanted him to take to ease his crippling back pain.
Le Gall said on Thursday that Ribery had withdrawn from the squad because he was afraid of injections.
The 31-year-old Bayern winger said he had simply refused the cortisone injection.
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"I am not scared of injections. But I did not want to be injected with cortisone by the French doctor," Ribery told the SID sports agency of Germany, an affiliate of AFP, in a written statement.
"I know it is not good," he added.
"You can believe me," he said "my career is going to continue longer" without the cortisone.