On Saturday, American and British forces carried out fresh strikes against 18 Houthi targets in Yemen, in response to a wave of attacks by the group on Red Sea shipping.

"With such attacks, America and Britain seek to escalate tensions and crises in the region, and expand the scope of war and instability," Iran's foreign ministry spokesman Nasser Kanani said in a statement.

"Certainly, this kind of arbitrary and aggressive military operation, aside from aggravating insecurity and instability in the region, will not achieve anything for these aggressor countries," Kanani added.

He further condemned the United States and Britain for failing to "take immediate and effective action" to stop Israel's deadly campaign on Gaza.

The Houthis say their attacks on shipping around the Red Sea are in support of Palestinians in war-ravaged Gaza.

Regional tensions have soared since the war erupted, stoking violence involving Iran-backed groups in Lebanon, Iraq, Syria and Yemen.

Following the Saturday attacks, Pentagon chief Lloyd Austin said the US "will not hesitate to take action, as needed, to defend lives and the free flow of commerce in one of the world's most critical waterways".

The Houthis' military spokesman Yahya Saree said the attacks would continue until "the aggression stops" in Gaza.

The Islamic republic has previously said it sees a "duty" to support what it calls "resistance groups" in the region, but insists they are "independent" in decision and action.