NBA Star Assaults Fan?

The footage shows the Minnesota Timberwolves star jawing back and forth with a fan at Dyckman Park in New York City ... before finally losing his cool, shoving the fan in the face, and walking back towards the court.

Beasley went on to lead his team to victory over another park team led by NBA superstar Kevin Durant.

We're told the fan had been heckling Beasley throughout the game -- screaming taunts like, "You're a f**king bum ... you ain't sh*t Beasley."

Beasley approached the fan and said, "I've never been a bitch ... I'll show you that right now."