The government is planning for "a variety of developments" as other countries stepped up efforts to bring back citizens stranded in Israel.
The Foreign Office has advised against all travel to Israel, but Britons already in the country now face difficulties getting home 鈥� with the airspace closed due to the conflict with Iran.
A Number 10 spokesman said: "We, of course, recognise this is a fast-moving situation that has the potential to deteriorate further, quickly and without warning.
"We are keeping all our advice under constant review and we plan for a variety of developments, as you would expect."
Poland has announced an evacuation of around 200 of its citizens in a bus convoy to Jordan, while the Czech Republic and Slovakian governments have organised repatriation flights from the region.
Iran fired further missiles at Israel overnight, while Israel's military claimed to have "full air superiority" over Tehran as strikes continued.
The escalating conflict will be high on the agenda as leaders from the G7 group of wealthy democracies meet in Canada.
Sir Keir Starmer said that the G7 meeting in Alberta would provide an opportunity for allies to make the case for de-escalation in the 鈥渇ast-moving鈥� situation in the Middle East, with US president Donald Trump among those set to attend.
Starmer called for "restraint and de-escalation" during a bilateral meeting with Italian prime minister Giorgia Meloni in Kananaskis, Canada, on Sunday evening.