Kevin Garnett and Deron Williams were among four Nets wearing the shirts in support of the family of Eric Garner, who died July 17 after a police officer placed him in a chokehold when he was being arrested for selling loose, untaxed cigarettes.
"It was a message to the family. That I'm sorry for their loss, sorry to his wife. That's what it's about," James said after the Cavaliers' 110-88 victory. "I think everybody else gets caught up in everything else besides who's really feeling it, and that's the family. That's what it's about."
Chicago star Derrick Rose wore one before a game Saturday and James said Sunday he wanted one. He got it from Nets guard Jarrett Jack, who provided them to players on both teams. A few NFL players had the saying written on different items of gear and shirts during pregame warmups before games on Sunday, including St. Louis Rams guard Davin Joseph, Detroit Lions running back Reggie Bush and Cleveland Browns cornerback Johnson Bademosi.
Entertainer Jay-Z, a former part-owner of the Nets who still attends some games, also gave some of the shirts to the team.
"D-Will brought it to the guys that wanted to wear it and support the cause, and the ones that wanted to wear it wore it," Garnett said. "I think it is important."
James said he and Irving did not discuss their plans to wear the jerseys beforehand. Irving went to warm up first, and at that point James was still saying it was only a "possibility" that he would be wearing it.
"We're our own men, and we didn't talk about it," James said. "When we seen each other wearing the shirts, we looked at each other and just gave the nod. It goes from there."
The statement from the players came before a game that was attended by Britain's Prince William and his wife, Kate, as well as NBA Commissioner Adam Silver.
"I respect Derrick Rose and all of our players for voicing their personal views on important issues but my preference would be for players to abide by our on-court attire rules," Silver said.
Players are required to wear attire of Adidas, the league's official apparel provider.
A recording of Garner's arrest showed him gasping, "I can't breathe" during the fatal encounter, and thousands have protested a grand jury decision not to indict the officer since the announcement on Wednesday.
Over 200 protesters gathered outside the Barclays Center on Monday night, chanting "Hands Up, Don't Shoot" and "I can't breathe."
Irving said his thoughts were with Garner's family.
"What happened is a tragedy, I feel terrible about it, but my emotions are just more or less condolences for the family," Irving said.