Golden State's Stephen Curry was shooting free throws with 5:19 left in the third quarter when Green spoke to a game official, repeatedly pointing to a man sitting a few rows down the opposite baseline.
The officer met the security personnel at Phirserve Forum and the fan was taken out. Earlier in the period, the fan and Green had exchanged words.
"I was really close to going back and diving all the way in, but just went back and told the officer. And when I told the officer, he said, he should get out of here," Green said.
Following Milwaukee's 128–111 win, the Bucks said in a statement: "Under the discretion of the referees, we are investigating the situation and we are speaking with the NBA."