TEHRAN — Iran insists it is not talking directly to the United States, even as both sides prepare for new negotiations aimed at easing a five-month war that has shaken global energy markets. Instead, Tehran says its only active talks are with Oman, focused on keeping the strategic Strait of Hormuz open for shipping. “We are not currently negotiating with the United States. Our negotiations are with Oman to secure passage through the Strait of Hormuz,” Foreign Ministry spokesman Esmaeil Baqaei told reporters on Aug. 3. Baqaei called the Oman talks “constructive,” saying they were meant to agree on a new shipping corridor.