UK forces were involved in supporting Israel after Iran launched a missile attack on the country.
Defence Secretary John Healey, who will be in Cyprus on Wednesday to visit personnel, said British forces had "this evening played their part in attempts to prevent further escalation”, without giving more details.
It is understood RAF jets were involved in the efforts to intercept the Iranian missiles targeted at Israel.
The operation was similar to the role carried out by the UK’s forces when Iran launched a drone and cruise missile barrage at Israel in April, with RAF Typhoons involved in the defensive effort.
Prime Minister Sir Keir Starmer said the UK "stands with Israel" and recognises its right to self-defence.
He added he was “deeply concerned that the region is on the brink” and again urged British nationals in Lebanon to leave amid escalating violence in the Middle East.
Britons fleeing Lebanon were set to board a UK Government-chartered flight to safety on Wednesday.
The flight to get Britons out of the country is due to depart from Beirut-Rafic Hariri International Airport at a cost of £350 per seat.
Healey (below) is visiting Cyprus to meet troops who are preparing for the possibility of evacuating British citizens from Lebanon.
Britons in Lebanon have been advised to register their presence with officials on the government's website.
But some told the BBC they had received no confirmation or details about their booking on the government-chartered flight, despite paying for a seat.
British citizen Libby, 25, was about to board a commercial flight from Beirut to Cairo on Wednesday morning, and described the situation in the Lebanese capital as "terrifying".
"You can't sleep because you can hear the Israeli drones over your head, you wake up in the night because you hear strikes," she told the BBC Radio 4's Today programme.
Iran said it launched the strikes in retaliation for the killing of Hezbollah leader Hassan Nasrallah in Beirut last week, the Associated Press reported.
The escalation came after Israel began a ground offensive in Lebanon, carrying out what it described as “limited, localised” operations.
The Iranian attack on Israel began while Starmer was talking to Israel’s Prime Minister Benjamin Netanyahu on Tuesday, Downing Street said.
Lebanese officials say more than 1000 people have been killed following Israeli air strikes over the past two weeks.
