NEW DELHI, June 23. -Indian Foreign Minister Swaran Singh said today that if the United States is shipping munitions to Pakistan, "it is a clear departure from the assurances given me."

Singh was commenting on State Department acknowledgment yesterday that two Pakistani freighters recently left the United States with arms and other military supplies. The State Department said the arms were purchased before the ban went into effect March 25.

The Nixon Administration had announced a ban on military supplies to Pakistan after the government of President Yahya Khan moved to crush the eastern province's self-rule movement with troops in March. Singh returned today from a 15-nation tour, during which he conferred with President Nixon

Meanwhile, Indian Members of Parliament today demonstrated outside the American Embassy in protest against the U.S. arms shipment.