Prime Minister Rishi Sunak warned Iran-backed Houthis that Britain would stage new military action if the Yemeni rebels keep attacking shipping in the Red Sea.
"We are not seeking a confrontation," he told parliament hours after a second round of US-UK strikes.
"We urge the Houthis and those who enable them to stop these illegal and unacceptable attacks.
"But if necessary, the United Kingdom will not hesitate to respond in self-defense. We cannot stand by and allow these attacks to go unchallenged," Sunak added.
Royal Air Force jets struck two military sites just north of the Yemeni capital Sanaa, "each containing multiple specific targets, which the Houthis used to support their attacks on shipping," Sunak said.
He informed MPs that the government's initial evidence was that "all intended targets were destroyed".
Sunak added that the joint military operation with the United States, which followed similar strikes on January 11, were "working to degrade" the Houthis' capability to launch attacks.
He insisted the strikes were "limited", in line with international law and that no decision has been made to start a sustained campaign against the rebel group.
Since the first strikes, the United States has also launched individual air raids against missiles that Washington said posed imminent threats to civilian and military vessels.
But the Houthis have vowed to continue their attacks -- part of a growing crisis in the Middle East linked to the Israel-Hamas war, which has raised tensions across the region as well as fears of a broader war directly involving Iran.
The Houthis warned on Tuesday that the US-British strikes would not go "unanswered and unpunished".
