Ice Cube is escalating his beef with the royal family of Qatar -- warning the Emir not to threaten BIG3 players or ANY American athlete.
We broke the story -- Cube and his BIG3 partner, Jeff Kwatinetz, filed a $1.2 BILLION lawsuit against several Qatari investors ... including royal family member Sheikh Abdullah bin Mohammed bin Saud Al Thani.
Cube claims the investors screwed the league out of millions -- and then made threats saying, "You should think of your safety and the safety of you and your family."
Now with the Emir of Qatar visiting with President Trump on Tuesday, Cube decided to send a message ... taking out a full page ad in the NY Times saying:
"Hey President Trump, when you meet today with Putin's new friend, the Emir of Qatar, please tell him not to threaten the BIG3 and American athletes!"
Clyde "The Glyde" Drexler also added his name to the message.
For their part, the Qatari government is denying wrongdoing -- saying they are not connected to the group that invested in the BIG3.