Mike Joyce told the Carroll County Times that Zbikowski was "shocked" to learn that he had tested positive and was punished by the Chickasaw Nation Boxing Commission. Zbikowski, who has taken to boxing during the NFL lockout, improved to 4-0 after scoring a first-round knockout of Blake Warner on Saturday night in Thackerville, Okla.
The boxing commission tested all fighters on the card and suspended five.
Zbikowski, a 5-foot-11, 215-pound cruiserweight, is scheduled to fight May 21 in Cabazon, Calif., and again June 4 at Staples Center in Los Angeles.
Joyce told the Chicago Sun-Times earlier Tuesday that Zbikowski would appeal the drug test because it was in error.
"After the fight, all the fighters tested were positive," Joyce said. "They had you pee in a cup and put a strip of something in there. I've never seen results where you get them the day of the fight. It was like a home pregnancy test or something.
"He's taken all sorts of tests for the NFL and he's never tested positive ... ever," Joyce added.
The Ravens posted a statement on their Twitter page Tuesday: "We're aware of the story about Tom and the test. As of now, unfortunately, we are unable to reach out to him for his side of the situation."
Zbikowski previously has received the support of Ravens owner Steve Bisciotti, who called the safety's exploits in the ring "awesome."
Zbikowski, a three-year NFL veteran, has yet to sign his contract with the Ravens as a restricted free agent, and he could become an unrestricted free agent in 2012, depending on the new collective bargaining agreement.