There was a smattering of boos when players from FC Dallas and Nashville SC collectively took a knee during the national anthem before their MLS game on Wednesday night in Frisco, Texas.
Dallas defender Reggie Cannon said he was disgusted by the boos at Toyota Stadium when players and officials knelt to call attention to racial injustice.
Dallas and Nashville had not played a game since the season was suspended on March 12 because of the coronavirus.
The death of George Floyd has spurred a number of MLS players to form the group Black Players for Change, which seeks to address systemic racism in soccer and society.
At the opening game of the MLS tournament in Florida, members of the group collectively stood in silence, fists raised, for more than eight minutes.