The US Olympic Committee on Monday backed shot putter Raven Saunders after she made the first protest on a medal podium at the Tokyo Games.
The 25-year-old African-American athlete crossed her arms in an "X" gesture during Sunday's medal ceremony at the Olympic Stadium after claiming silver.
US media outlets reported that Saunders, who is an outspoken supporter of LGBT rights, said her gesture was made in solidarity with "oppressed people".
After clinching a silver medal, she said that she wanted to represent "people all around the world who are fighting and don't have the platform to speak up for themselves".
The USOPC said it had decided the protest did not violate its own regulations and that it was in discussions with the IOC about the issue.
"The USOPC conducted its own review and determined that Raven Saunders' peaceful expression in support of racial and social justice that happened at the conclusion of the ceremony was respectful of her competitors and did not violate our rules related to demonstration," it said in a statement.
The USOPC softened its approach to athletes protesting on the podium after a review of rules following nationwide protests in the United States last year in the wake of the killing of George Floyd.
Saunders' protest is the first test of International Olympic Committee rules which ban protests of any kind on the medal podium at the Olympics.
The IOC tweaked its rules regarding athlete protests ahead of the Games, saying that peaceful protests before competition would be allowed.
However the Olympics governing body has maintained a strict rule against protesting on the medal podium.
Asked earlier Monday about the protest, IOC spokesman Mark Adams said the body was in touch with the US Olympic Committee and World Athletics.
"We are, not surprisingly, looking into the matter and we'll now consider our next steps," he added, declining to be drawn further on possible consequences.
"I think we need to fully understand what's going on and then take a decision from there," he added.
Updated IOC guidelines released last month say that disciplinary consequences for protests will be "proportionate to the level of disruption and the degree to which the infraction is not compatible with Olympic values".
It said an extensive survey of athletes showed most wanted to "protect the field of play".
Experts say the IOC is unlikely to take a heavy-handed approach against athletes for protesting in Tokyo, mindful of the possible public relations backlash that would likely follow any sanction.