The federal government acted after images of officers in the St Louis suburb wearing the bracelets were posted online.
Wilson is the white officer who killed unarmed black teenager Michael Brown on August 9, sparking protests that are still taking place.
Wilson, who shot the 18-year-old six times in unclear circumstances, has not been charged and remains on paid leave.
The Department of Justice wrote to Ferguson police chief Thomas Jackson to explain the bracelets had “upset and agitated” residents, many of whom said the police wearing them had also illegally used black tape to cover up plates identifying them.
Darren Wilson testified in front of grand jury
St Louis Public Radio reports: If Officer Wilson Is Not Indicted, McCulloch Vows To Release Grand Jury Transcripts, Recordings
110 more days until Grand Jury deadline.