MEXICO CITY, - "Chill, relax" was Gianni Infantino's message on Wednesday as the FIFA president sought to defuse concerns over visa issues that have clouded the buildup to the World Cup, saying soccer's governing body could not dictate immigration decisions to host nations.Speaking on the eve of the tournament opener between co-hosts Mexico and South Africa, Infantino addressed concerns surrounding Somali referee Omar Abdulkadir Artan, who was barred from entering the U.S. despite having a valid visa."It is unfortunate what happened to the referee from Somalia," Infantino told a press ‌conference, his first in ⁠three years."We ⁠try, we'll discuss, we'll see. Maybe sometimes it's good as well to chill, relax. We work on everything, we try to resolve everything."We are not the kings ​of the world who can rule over governments and police forces. We are a sports organisation."The case has drawn attention to immigration challenges ​ahead of the June 11-July 19 tournament after U.S. authorities said Artan was denied entry because of his links to "suspected members of terror organizations".Infantino said FIFA was continuing to work behind the scenes to resolve outstanding issues but stressed that immigration decisions ultimately ​rested with national authorities."We always try to find solutions," he said. "Sometimes to immediately start ⁠screaming and shouting ‌has the opposite effect of finding a solution."Asked whether visa-related controversies had made him regret selecting ​the U.S. as one ​of the host nations, Infantino said he had no regrets."There are issues; it's normal for an ⁠event of this magnitude," he said. "Some come from the United States, some from ​Canada, some from Mexico. We deal with all of them."The FIFA president also pointed to ​Iran's participation in the tournament as evidence of his organisation's efforts to navigate complex political circumstances."People were saying Iran couldn't come to the World Cup," Infantino said. "I promised them they will come."He said ensuring Iran's participation despite geopolitical tensions demonstrated football's ability to bring people together.WE WANT TO UNITE THE WORLDThe Swiss-Italian executive repeatedly returned to a message of unity, saying the World Cup could provide a welcome distraction at a time of global conflict and uncertainty."When Iran plays, the stadium will be full and I hope ‌there will be a positive atmosphere because this is football," he said. "We want to unite the world."Infantino also defended FIFA's ticket pricing after criticism from some supporters who argued that the cost of attending ​matches had become prohibitive.FIFA ​has sold more than six million ⁠tickets for the tournament, which now has 48 teams, and demand had exceeded expectations by "a factor of 10 or more", he said."The starting price at $60 is the lowest entry price of any of the American sports in the playoff phases," Infantino said."If you ​sell it at a lower price point, it would have gone on secondary markets at much higher prices. Every dollar that comes in goes back to the development of football."The World Cup kicks off on Thursday at Mexico City's Estadio Azteca, which will become the first stadium to host matches at three men's World Cups, with Infantino predicting one of the most competitive tournaments in the events history.The FIFA president said factors including altitude, climate, travel and the expanded format would add further unpredictability before concluding: "Let the celebration begin."