British planes have reportedly shot down Iranian drones and missiles fired at Israel.
In a statement, Defence Secretary Grant Shapps said he had authorised the deployment of additional Royal Air Force assets to the region that would "intercept any airborne attacks within range".
Israel’s Channel 12 reported that UK and American fighter jets shot down Iranian drones near the Iraq-Syria border.
The Ministry of Defence would not confirm that the RAF had engaged Iranian assets.
Rishi Sunak has condemned Iran's "reckless attack" and declared that Britain will "continue to stand up for Israel's security".
The Western forces were scrambled after Iran fired hundreds of drones and missiles in its first direct attack against Israel.
99 per cent were successfully blocked from reaching their target, the IDF has said, in part thanks to a coalition of Western and Arab states aiding Israel’s defence.
US President Joseph Biden said: “At my direction, to support the defence of Israel, the US military moved aircraft and ballistic missile defence destroyers to the region over the course of the past week.
“Thanks to these deployments and the extraordinary skill of our service members, we helped Israel take down nearly all of the incoming drones and missiles."
Shapps said: "I strongly condemn the senseless airborne attack that Iran has launched on Israel. It serves no benefit other than to further undermine regional security.
"We continue to work with Israel and partners in the region to prevent further escalation. Peace and stability are in everyone's interest, and I urge Iran to immediately end all forms of destabilising behaviour.
"In response to escalation in the region and in partnership with our allies, the Prime Minister and I have authorised the deployment of additional Royal Air Force assets.
"The RAF jets and air refuelling tankers will bolster our existing Operation Shader - the UK's existing counter-Daesh operation in Iraq and Syria. In addition, these jets will intercept any airborne attacks within range of our existing missions, as required."
Speaking to the BBC, Health Secretary Victoria Atkins said she could not confirm or deny whether British planes had shot down Iranian drones.
Asked if Cabinet was consulted before jets were deployed, she said the "circle of knowledge" had to be "very, very tight".
On Sky News, she said: “Our message across the region and with our partners is that we must not escalate this.
"We must contain this and just take time to look at what has happened over the last 12 hours.
“All of our efforts at the moment are on de-escalating this. We do not want this to go any further because we can all see the human cost to this, and we do not want a miscalculation or an escalation in events because we know that that will take its toll.”
British ships have recently been deployed to protect commercial shipping from Houthi attacks and have launched air strikes to combat the Iran-backed group, which controls much of Yemen.