Robert Iler, 16, who plays Tony Soprano Jr. on the HBO mob hit “The Sopranos,” was arrested near his New York apartment early Wednesday on robbery and drug possession charges. He was among four teens picked up by police for allegedly strong-arming two 16-year-olds out of about $40 just after midnight, say authorities, who added that Iler allegedly had a small bag of marijuana and a water pipe in his pocket. He pleaded not guilty to the charges at his arraignment Wednesday night and was released after posting $2,500 bail. His next court date was set for July 9. “He was just in the wrong place in the wrong time,” Iler’s lawyer told reporters. He would not comment on the marijuana charge. Helen Iler, the actor’s mother, told The New York Times that her son had never been in trouble before. “This is the first, and it will be the last.” HBO declined comment. Police told The Times that Iler and the others cracked jokes in their jail cell. “They weren’t exactly holding their heads and saying, ‘Oh my god, what have I done?’ ” said a supervisor. This season on the show, Iler’s character was expelled from school for stealing a math test and urinating on school property.