Antetokounmpo immediately got into it with Wagner after the play ... and went after him with a good ole Zinedine Zidane-esque headbutt.
The NBA announced Giannis' punishment on Wednesday ... saying he will miss the next Bucks game against the Memphis Grizzlies.
"Milwaukee Bucks forward Giannis Antetokounmpo has been suspended one game without pay for headbutting Washington Wizards center Moritz Wagner during a stoppage in play," the league said in the official statement.
"The incident, for which Antetokounmpo was assessed a Flagrant Foul 2 and ejected, occurred with 8:50 remaining in the second quarter of the Bucks’ 126-113 win over the Wizards on Aug. 11 at Visa Athletic Center on the campus of ESPN’s Wide World of Sports in Orlando."
It's really NBD for the Bucks -- Milwaukee has already clinched the 1st seed in the Eastern Conference ... and have a legit chance at making a push for the NBA Finals ... as long as Giannis keeps his cool.