"We obviously have been watching this carefully. There are no US citizens as far as we know who are on the ship or otherwise involved," White House Press Secretary Josh Earnest told reporters at his daily news conference.
"But what we have been talking about more than usual in this room over the last couple of weeks is the vested US interests in the free flow of commerce in this region of the world," he said when asked about the continued detention of the ship by Iran.
The Maersk Tigris was diverted on April 28 by Iranian patrol boats in one of the world's major oil shipping lanes.
The Iranian action prompted the United States to send vessels to monitor the situation and to accompany US-flagged vessels passing through the strait.
Danish shipping giant Maersk has insisted on the release of the vessel and its 24 crew members.
Iran says the Maersk Tigris would only be let go once a years-old debt case is settled.