LONDON — Britain took new steps on Monday to distance itself from the Trump administration’s escalating confrontation with Iran, even while pushing for the release of an oil tanker seized by Tehran three days earlier.

British efforts to bolster maritime security in the Persian Gulf “will not be part of the U.S. maximum pressure policy on Iran,” Foreign Minister Jeremy Hunt said after an emergency cabinet meeting about the tanker.

Mr. Hunt’s pointed statement was the first indication that a broad disagreement over Iran still persists between the two allies despite the Iranian seizure of the British-flagged tanker on Friday.

On the American side of the divide, Secretary of State Mike Pompeo insisted on Monday that both the British and American disputes with Iran arose from the same essential cause: the fundamental character of the Iranian government.