1:22 PM PST -- Roy Richter -- who serves as the president of the Captains Endowment Association, a union that reps Emanuel Gonzalez -- tells TMZ ... the allegation that Gonzalez told fellow officers to shoot 50 Cent on sight last year is completely false. Richter tells us Gonzalez never said that, and that he completely denies any suggestion he did. In fact, Richter says it was 50 who put Gonzalez's safety at risk by publishing a threatening Instagram post.

10:00 AM PST -- 50 Cent has responded to the Daily News article on Instagram saying, "I take this threat very seriously," and he is consulting with his legal counsel all the while posting a photo of Emanuel Gonzalez.

An NYPD officer is under investigation for allegedly telling his fellow cops to shoot 50 Cent on sight ... TMZ has confirmed.

Police sources tell TMZ, Commanding Officer Emanuel Gonzalez made the comment last June during roll call at the 72nd Precinct. What apparently triggered his comment ... 50 was scheduled to attend an NYPD boxing match in the Bronx. Gonzalez said, "Shoot him on sight."

Gonzalez has had beef with 50 ... according to the NY Daily News, which broke the story, a month before Gonzalez made his comment he filed an aggravated harassment complaint claiming 50 threatened him on Instagram.

50 had accused Gonzalez of "shaking down" the owner of one of 50's go-to clubs ... this according to the Daily News. 50 wrote on his Instagram, "Get the strap" -- slang for gun. Gonzalez says 50's followers subsequently threatened him with violence.

We're told Gonzalez has said it was just a joke, but the matter was reported to higher-ups in the Department and Internal Affairs is now investigating.

Gonzalez is a long-timer in the Department -- 30 years -- and he's still on duty.

50's rep tells TMZ," Mr. Jackson takes this threat very seriously and is consulting with his legal counsel regarding his options going forward. He is concerned that he was not previously advised of this threat by the NYPD and even more concerned that Gonzalez continues to carry a badge and a gun."