The Magic, who trail 3-1 in the best-of-seven, first-round series, left the court when it was clear the Bucks were not going to play.
The Athletic reported that the Bucks players were in the locker room attempting to reach Wisconsin attorney-general Josh Kaul. Citing sources, the online publication said the Magic would not accept a forfeit of the game.
The report added that the Houston Rockets and Oklahoma City Thunder were also planning to boycott their Game 5, which was scheduled to be played later on Wednesday.
The Bucks did not immediately respond to a request for comment.
The boycott comes as a teenager identified as Kyle Rittenhouse was arrested and charged with homicide on Wednesday after gunfire killed two people and wounded a third during protests over the police shooting Blake, court officials said.
The lakeside city of Kenosha been rocked by civil unrest since Sunday, when police shot Blake, 29, in the back at close range. That incident, captured on video, has reignited protests over racism and police use of force in the United States.
Rittenhouse, 17, was arrested on a warrant in Illinois and charged with first-degree intentional homicide in Kenosha, a Lake County court official said.
The third night of protests in the city of 100,000 between Milwaukee and Chicago erupted in gunfire shortly before midnight, prompting some elected officials to call for a reinforcement of National Guard troops or the deployment of federal law enforcement officers.
Republican President Donald Trump on Wednesday said had spoken with Democratic Wisconsin Governor Tony Evers, who had agreed to accept US law enforcement support.
“TODAY, I will be sending federal law enforcement and the National Guard to Kenosha, WI to restore LAW and ORDER!” Trump wrote on Twitter, without elaborating.
The violence coincided with the second night of the Republican National Convention, in which Trump has made “law and order” crackdowns on protest violence a campaign theme.
Democratic presidential nominee Joe Biden spoke on Wednesday (Thursday AEST) with Blake’s family, and emerged from the conversation calling for justice and condemning violent protest.
“I spoke to Jacob’s mom and dad and sister and other members of the family just a little bit earlier, and I told them justice must and will be done,” Biden said in a video posted to his campaign’s social media accounts.
The first two nights of protests in Kenosha were overtaken by outbreaks of vandalism and arson that destroyed several businesses. On the third night it turned deadly.
It was unclear what set off the gunfire, but the streets of Kenosha were teeming with a combustible mix of protesters and armed militia members, who had been guarding local businesses.
“What it seems to be is a member of a militia group who decided to be a vigilante and take the law into his own hands and mow down innocent protesters,” Wisconsin Lieutenant Governor Mandela Barnes told MSNBC television on Wednesday before the arrest was reported.
Video on social media showed the shooter was a white man with a rifle.
Rittenhouse’s now-deleted Facebook page shows him posing with another young man, both of them holding rifles. The photo is encircled by a Blue Lives Matter badge in support of police.