Two Japanese teenagers have been banned indefinitely from J-League matches for a slur against the coach of a rival club, officials said Monday. The boys, who were not identified, hung a banner addressed to Afshin Ghotbi, the Iranian-American manager of Shimizu S-Pulse, before their league match against rivals Jubilo Iwata on May 28. \"To Ghotbi. Stop making nuclear weapons,\" the banner read in Japanese as it was unfolded from the second level of Shimizu\'s Nihondaira Stadium, video footage showed. The banner was quickly taken away but dozens of angry Shimizu supporters scuffled with the teenagers and other Jubilo fans without any major violence breaking out, press reports said. \"The supporters (who displayed the banner) have been already punished by the club,\" J-League public relations official Rina Iwamoto said, confirming the ban. The exact intent of the banner was not clear, but the United States has slapped unilateral sanctions on Iran on top of punitive measures imposed by the United Nations over Tehran\'s refusal to halt nuclear activities. J-League officials interviewed the presidents of Shimizu and Jubilo last week, she added. \"We are not certain how to deal with the clubs as we are checking regulations and precedents,\" she said. Ghotbi, 47, took the helm at Shimizu after coaching Iran from 2009 to the Asian Cup in Qatar in January.