Kenneth Edwards said in a statement Tuesday he was notified about the results a month ago and he is awaiting results of a backup sample.
Edwards says he has not competed since July and there was no practical reason to use a diuretic for any kind of preparation. He says he will challenge the findings.
The announcement comes as the world's anti-doping authority launches a sweeping audit of Jamaica's drug-testing agency amid allegations of inconsistent testing.
Doping investigations also are underway involving other Jamaicans, including sprint stars Veronica Campbell-Brown, Asafa Powell and Sherone Simpson.