By Sue Zeidler LOS ANGELES, Jan 31 (Reuters) - Coca-Cola Co held what it called a "productive conversation" with an Arab-American group that labeled the firm's Super Bowl ad racist, but will not change the commercial featuring an Arab walking through a desert with a camel. "We did express regret that the ad had been misunderstood," Coca-Cola spokeswoman Lauren Thompson said in an email. "We are very concerned by these allegations and in no way is our ad meant to be derogatory to any group."