Tim Weah and other members of the U.S. national team were targeted with racist abuse on social media after the Americans were beaten 2-1 by Panama in the Copa América on Thursday night.
U.S. Soccer Federation issued a statement saying it was "deeply disturbed with the racist comments made online."
Weah, who is Black, was sent off with a red card in the 18th minute after punching a Panama player.
It was earliest red card for a U.S. player since Jimmy Conrad was tossed from a 2010 friendly against Honduras.
The short-handed Americans nearly held on for a tie, but Panama scored a late goal that put the U.S. hopes of advancing past the first round in serious jeopardy.
U.S. Soccer said several of its players were the targets of racist comments.
"There is absolutely no place in the game for such hateful and discriminatory behavior," the statement said. "These actions are not only unacceptable but but also contrary to the values of respect and inclusivity that we uphold as an organization."
U.S. Soccer will be offering mental health services to any player of staff member who requests it. The governing body also reported the racist abuse to CONMEBOL, the South American organizers of the tournament.
Weah issued a public apology on social media for a loss of composure that cost his team dearly.
"No matter what, I will always fight for my team and my country till the day I am no longer needed or capable to!" he said. "I sincerely apologize to everyone. My love for this team goes beyond just football and I am so sad and angry at myself for putting my brothers through what they went through tonight."
