Olympic officials said on Monday they were "looking into" US shot putter Raven Saunders after she made the first podium protest of the Games, risking possible disciplinary action.
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 black and an outspoken supporter of LGBT rights, said her gesture was made in solidarity with "oppressed people".
After clinching her silver medal on Sunday, Saunders said she wanted to represent "people all around the world who are fighting and don't have the platform to speak up for themselves."
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 about the protest, IOC spokesman Mark Adams said the body was in touch with the US Olympic committee and track and field's governing body, 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 make 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".
The United States Olympic and Paralympic Committee said before the games it will not sanction its athletes for protesting.
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.
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.