QATAR - Son Heung-min said Thursday "comments that cross the line" had been aimed at his South Korea team-mates at the Asian Cup and called for "protection" from abuse.
The Tottenham Hotspur forward said criticism of the team "really hurts us", without going into specifics, adding that players had been subjected to "comments that I can't even repeat".
South Korea advanced to the knockout rounds of the tournament in Qatar despite conceding a last-minute equaliser in a 3-3 draw with Malaysia, who are ranked 130th in the world.
"Some of the boys are being criticised or getting comments that cross the line," the skipper told reporters after the game.
"It really hurts as a team-mate to see the boys in pain.
"We are working very hard on the pitch, we are trying to give everything for the fans and for the country."
Son did not specify the type of abuse or where it came from.
"Before they are players they are people," he added.
"They have families back home, some of them have kids. It really hurts and I'm really asking a favour to protect us."
Japan goalkeeper Zion Suzuki said Monday that he was racially abused on social media following his team's shock defeat to Iraq.
Coach Hajime Moriyasu said Suzuki, whose father is Ghanaian-American and mother Japanese, had "the full support" of Japan's squad.
Moriyasu said Thursday that any kind of abuse "can really hurt players mentally".
"In the worst case it could cause them to quit football or even want to end their own lives," he said.
"I want to make sure they are looked after in my team."