A British-born youth team coach with Socceroo Tim Cahill's club New York Red Bulls was fatally slashed in one of the city's busiest neighbourhoods.

Michael Jones, 25, from Liverpool, had his neck and torso slashed and his ear cut off early on Sunday and was taken to hospital where he was pronounced dead.

Cahill, who joined the Red Bulls this season, expressed his condolences via his Twitter account.

"So sad to hear the news about Mike Jones a coach @NewYorkRedBulls, my thoughts are with his family and friends," Cahill tweeted.

Jones was on 14th Street in Manhattan's Union Square at around 4:30am on Sunday when he was seen arguing with a man.

The coach had earlier been out with his girlfriend but they parted around midnight, police said.

Police late on Sunday released surveillance footage of the suspected slasher, a man with a ponytail wearing a dark jacket.

The New York Red Bulls issued a statement, describing Jones as a "fantastic coach who loved soccer."

"This is truly a sad day for our soccer community and we will do our utmost to help authorities in their investigation of this case," it said.

"Our thoughts and prayers are with Michael's family at this time," the statement said.