WASHINGTON — The aircraft carrier Theodore Roosevelt and a guided missile cruiser were headed to the waters off Yemen on Monday to join 10 other American warships as a warning to Iran about its shipments of weapons to rebels there, American officials said.

The Obama administration cast the deployment primarily as a show of force, but acknowledged that the flotilla could be used to interdict any supplies of Iranian arms to the Houthi rebels. The warships are also meant to reassure Saudi Arabia, an American ally that has been carrying out a bombing campaign against the rebels in Yemen.

“This is really about sending a message,” said an American official who declined to be identified as discussing a continuing military operation. “It is a message to our partners that we are in this and willing to support. It is a message to the Iranians that we’re watching.”

White House officials acknowledged that they were compartmentalizing policy on Iran by confronting the country’s aggressive posture in the region even as American diplomats tried to complete an agreement with Iran to limit its nuclear program.