WASHINGTON — Washington Nationals general manager Mike Rizzo went on the attack Monday after Phillies ace Cole Hamels plunked star rookie outfielder Bryce Harper.

Hamels admitted he intentionally hit the 19-year-old phenom in the first inning Sunday night, telling reporters afterward it was his way of saying, “Welcome to the big leagues.“

But Rizzo was not amused, telling The Washington Post Monday the Phillies’ left-hander was “fake tough” and should be suspended for the act.

“I’ve never seen a more classless, gutless chicken [bleep] act in my 30 years in baseball,” Rizzo told the paper.

Major League Baseball on Tuesday suspended Hamels five games for the act.

Hamels, who held the Nationals to one run with eight strikeouts in eight innings, drilled Harper in the back with two outs in the first inning.

“I’m just trying to continue old baseball, because I think some people get away from it,” Hamels said after the Phillies’ 9-3 win in Washington.

Harper did exact a measure of revenge by stealing home later in the inning to give the Nationals an early 1-0 lead.

Nationals pitcher Jordan Zimmermann also appeared to send Hamels a message when the Phillies starter was hit by a pitch while attempting a bunt in the third inning.

Zimmerman maintained afterward the errant pitch was not intentional.