US Secret Service spokesman Edwin Donovan has been quoted as saying, "We're aware of the incident, and we're going to take appropriate investigative steps." The matter was first exposed by The Washington Post newspaper.
The accused, according to the newspaper report, said that the policeman worked as a motorcycle escort for official motorcades in the US capital. He was overheard saying that he would shoot Obama and also showed off the weapon that he intended to use on his cell phone.
The newspaper added that the police officer was immediately moved to administrative duty and the incident was reported to the Secret Service that is in charge of protecting the US President and his family.
Police spokeswoman Gwendolyn Crump has been quoted as saying to the Washington Post, "We received an allegation that inappropriate comments were made. We are currently investigating the nature of those comments."
The office of Michelle Obama did not make any comment on the report.