The United States has identified mines recovered from the Persian Gulf as probably Iranian, Defense Secretary Caspar W. Weinberger said yesterday.

Saying he did not want to get into specifics, Weinberger confirmed in a television interview that U.S. forces have found mines outside Kuwait harbor that he said probably were from Iran.

Meanwhile, three Kuwaiti tankers and three U.S. warships making up the second U.S.-escorted convoy to travel through the gulf were reported to have come to a virtual standstill after passing Bahrain, the halfway mark of the 550-mile journey. Shipping sources speculated the ships may have spotted fresh mines and may await arrival of U.S. Sea Stallion helicopters equipped for mine-sweeping. The convoy had been expected to arrive at Kuwait's main oil terminal early today.

In Beirut, Iranian Ambassador Ahmad Dastmalchian threatened Saturday to transfer terrorism to American cities.

If the United States commits "any foolish deed" against Iran.

"We say that in the case of any foolish deed by the United States against us . . . we will transfer terrorism that is being practiced against us to the streets of Washington and the galleries of the White House," he told a rally of the pro-Iranian Hezbollah in a Shiite suburb of Beirut.