U.S. Marshal Kicks Small Dog Twice in Shocking Video Taken During Arrest

10:17 AM PT -- A spokesperson for the U.S. Marshals Service tells TMZ ... the incident was "unfortunate," but there was no malice involved, and the marshal reacted appropriately.

We're told ... the dog in question was being aggressive with a working K-9, and the owner of the dog was told repeatedly to control their dog. The agent finally reacted to keep the dog away from the K-9 ... the spokesperson adding, "An uncontrolled, aggressive animal can hinder official duties and threaten safety."

A U.S. Marshal has sparked outrage after he apparently kicked a small dog hard -- twice --while his counterparts made an arrest ... allegedly breaking one of the pup's ribs with the punts.

WREG-TV -- a local outlet in Memphis, Tennessee -- shared the sickening clip ... the vid shows the marshal, clad in tactical gear and blue jeans, turning toward the yapping dog rushing at officers.

Watch the video ... the little dog appears to be nipping at a leashed law enforcement K-9 at the scene ... the marshal boots the dog back toward the parking lot ... the same marshal delivers another swift kick in the courtyard as other officers wrestle with an individual in the foreground ... and the pooch yelps and rushes away before the clip ends.

As you can see, this isn't a big Rottweiler or a German Shepherd either ... it's a pretty small miniature schnauzer -- which will certainly generate more public scrutiny.

The woman who shared the video with WREG says her dog ran out of an apartment and was running around the yard while officers were arresting a man. It's unclear if it was her residence that was raided.

The dog was taken to a veterinarian, who reportedly diagnosed it with a broken rib.