The Government is under pressure from Labour to drop its opposition to a European Union ban on oil imports from Syria.
Following the co-ordinated call by western leaders for President Bashar al-Assad to stand down, the EU will this week discuss extending sanctions against the regime.
However Foreign Office minister Alistair Burt played down suggestions that the EU could follow the lead given by US President Barack Obama in banning Syrian oil imports.
He stressed that any new sanctions should target the regime and its supporters without hurting the Syrian people.
Shadow foreign secretary Douglas Alexander said he was "deeply concerned" at the Government's "equivocation" over sanctions on Syrian oil, which analysts say is a vital source of hard currency for the regime.
"Europe imports about 148,000 barrels of Syrian oil a day," Mr Alexander told BBC News.
"I hope that this week the European Union led by the British Government will join the action taken by the American government last week and move decisively in favour of broader sanctions, particularly in relation to oil exports.
"I really think it is imperative that the British Government acts."
Mr Alexander said that Britain should also consider recalling its ambassador in Damascus for discussions amid reports of continuing violence against anti-government protesters by the Syrian security forces.
"The Italians and the Swiss have already recalled their ambassadors. I think there is a case to send a very clear message to President Assad that the international community is determined to strengthen that isolation," he said.
