"We want [Syrian President Bashar] Assad to go," the Voice of America quoted British Prime Minister David Cameron as saying.
During a Wednesday visit to a camp in Jordan that houses 30,000 Syrian refugees, Cameron said, "we want to see a peaceful, political transition and a safe country for the future. But right now, the international community has to recognize, that what we have done is not enough."
Britain will soon begin talks with Syrian opposition groups, Foreign Secretary William Hague said in a written statement to the British Parliament. However, Britain will not supply the rebels with arms, he said.
Syrian allies Russia and China have repeatedly blocked attempts by the United Nations to increase sanctions against the Assad regime.
On Friday, Assad repeated warnings against the international community getting involved in Syria's internal conflict.
Alia Brahimi of the London School of Economics said Britain should focus on resolving the situation politically. Increasing military support would only exacerbate the conflict, he said.
Creating a united political front may be the only way to bring peace to Syria, said Michael Kerr of King's College London.
China and Russia will continue to resist efforts to topple Assad "without something that will replace him that does not negate their interests in Syria," he said.
Assad, in an interview televised Friday, told other nations to butt out.
"It is not about reconciling with the people, and it is not about reconciliation between the Syrians and the Syrians; we do not have a civil war," VOA quoted Assad as saying. "It is about terrorism and the support coming from abroad to terrorists to destabilize Syria. This is our war."