President Biden says the US has delivered a “private message” to Iran about the Houthis in Yemen after the US carried out a second strike on the group.
“We delivered it privately and we’re confident we’re well-prepared,” he said without giving further details.
The US said its latest strike was a “follow-on action” targeting radar.
Iran denies involvement in attacks by the Houthis in the Red Sea.
Tehran is however suspected of supplying the Houthis with weapons, and the US says Iranian intelligence is critical to enabling them to target ships.
Joint UK-US airstrikes targeted nearly 30 Houthi positions in the early hours of Friday with the support of Western allies including Australia and Canada.
A day later, the US Central Command said it carried out its latest strike on a Houthi radar site in Yemen using Tomahawk land attack cruise missiles.
A Houthi spokesman told Reuters the strikes had no significant impact on the group’s ability to affect shipping.
The Houthis are an armed group from a sub-sect of Yemen’s Shia Muslim minority, the Zaidis.
Most Yemenis live in areas under Houthi control. As well as Sanaa and the north of Yemen, the Houthis control the Red Sea coastline.
Reports say the ongoing air strikes on Houthi targets are quite separate from the war in Gaza, adding that they are “a necessary and proportionate response” to the unprovoked and unacceptable Houthi attacks on commercial shipping in the Red Sea.
In Yemen and the wider Arab world they are viewed rather differently.
There, they are seen as the US and UK joining in the Gaza war on the side of Israel, since the Houthis have declared their actions to be in solidarity with Hamas and the people of Gaza.