The announcement came from Revolutionary Guard spokesman Hossein Mohebi, who said the exact area would be announced shortly.
"If a ship travels in the area without having coordinated its journey, it will be subject to our sanctions," he said on Iranian state television.
Iran has been blocking the Strait of Hormuz since the war began with American and Israeli attacks on February 28. The United States has responded with a blockade of Iranian ports.
Talks are ongoing between Iran and Oman over temporary shipping lanes in the Strait of Hormuz. On Tuesday, Tehran said that ten ships that had not coordinated their passage with Iran had been attacked.
