Mayor de Blasio is refusing to allow a group of military veterans to march on Staten Island on Memorial Day — after welcoming public pot smokers to puff their way down Broadway in last week’s Cannabis Parade. “It’s a slap in the face,” Jamie Gonzalez, 57, a Marine infantryman who saw combat in Iraq during Operation Desert Storm, told The Post. Gulf War vets like Gonzalez were set to be given special honors in Staten Island’s 102nd annual Memorial Day Parade this year to mark the 1991 conflict’s 30th anniversary — until the city pulled the plug. “For many of us, a parade is a form of closure,” Gonzalez said. “We gather together and support each other.” “I’m incensed,” said Ted Cohen, 82, a retired Air Force reservist who was on alert through the Cuban Missile Crisis. “It’s pathetic.” The United Staten Island Veterans Organization, the association of 16 local vets’ groups that has sponsored the annual march for decades, filed a request for a parade permit with the NYPD on Feb. 27, following the same procedure they use every year in keeping with the city’s official rules.