Iran Players Sing National Anthem In Wake Of Reported Threats Against Families

Iran officials have reportedly threatened the families of their national soccer team's players ahead of their huge game with the U.S. -- insisting if they don't "behave" for the contest, "violence and torture" could ensue back home.

CNN, citing a World Cup security source, reported Monday that members of the Iranian Revolutionary Guard Corps met recently with its country's players to get the point across.

Iranian players had previously shown support for protestors in their home country by refusing to sing its national anthem before its game against England back on Nov. 21. But, before their game against Wales just days later, players once again participated in the song.

According to CNN, the IRGC has made it clear to players it expects no further protests in the World Cup -- including when the team kicks off its hugely important contest with the U.S. on Tuesday ... or the consequences could be dire.

Circumstances surrounding the group stage matchup had already been tense ... after the U.S. altered an Iranian flag on social media this past weekend to show support for the protests in the foreign country.

Iran's state media had asked FIFA to boot the U.S. out of World Cup action over it all.

USMNT head coach Gregg Berhalter ended up apologizing Monday for the posts ... but insisted he and his team had nothing to do with them, and were solely focused on Tuesday's game.

The contest is set to kick off at 11 AM PT.