Rishi Sunak has confirmed British jets shot down “a number” of Iranian drones launched during its attack on Israel.
The prime minister said Tehran was “determined to sow discontent and destabilise the region” and the UK would “stand by the security of Israel”.
“I can confirm that our planes did shoot down a number of Iranian attack drones,” he said on Sunday.
He paid tribute to RAF pilots “flying into the face of danger to protect civilians”.
“What we now need is for calm heads to prevail,” Sunak added.
Joe Biden has said United States forces helped Israel down “nearly all” of them.
The Israeli military said the vast majority were intercepted outside Israel’s borders.
More British jets were sent to the region following the attack. The Ministry of Defence said the RAF would bolster “existing missions” in Iraq and Syria and “intercept airborne attacks within range”.
Israel and Iran have been on a collision course throughout Israel’s six-month war in Gaza.
It is the first time Iran has launched a direct military assault on Israel, despite decades of enmity dating back to the country’s 1979 Islamic Revolution.
The attack came less than two weeks after a suspected Israeli strike in Syria that killed two Iranian generals in an Iranian consular building.
Iran had vowed revenge since the April 1 airstrike, which Tehran accused Israel of being responsible for. Israel has not commented.
In a broadcast clip this afternoon, Sunak said: “Last night Iran launched a barrage of missiles and attack drones across the Middle East towards Israel.
“This is a dangerous and unnecessary escalation which I have condemned in the strongest terms.
“Thanks to an international co-ordinated effort, which the UK participated in, almost all of these missiles were intercepted, saving lives not just in Israel but in neighbouring countries like Jordan as well.
“It’s clear that Iran is determined to sow discontent and destabilise the region - it’s own backyard - that’s very clear from its actions.”