UNITED NATIONS, Sept 23 (Reuters) - The United States informed Iran in advance of its intention to strike Islamic State militants in Syria and told Tehran that it would **t target the forces of Syrian President Bashar al-Assad, a senior Iranian official told Reuters. "This issue was first discussed in Geneva and then was discussed thoroughly in New York where Iran was assured that Assad and his government will **t be targeted in case of any military action against Daesh (Islamic State) in Syria," the official said on condition of a**nymity. ...