The group of 11 countries, Britain, Egypt, France, Germany, Jordan, Italy, Qatar, Saudi Arabia, Turkey, the UAE and the US, dubbed as 'Friends of Syria', discussed ways to ensure that the Geneva conference must be about a political transition in Syria away from the Bashar al-Assad regime.
UK foreign secretary William Hague, after the talks said, Syria's moderate opposition should "commit itself fully" to planned peace talks.
"The reason we have to make sure we are supporting and dealing with the moderate opposition committed to a democratic, pluralistic, non-sectarian future for Syria is precisely because if they don't have a role, then all the Syrian people have got left is a choice between Assad and extremists," he said.
"The longer this conflict goes on, the more sectarian it becomes. That's why we're making a renewed effort with Geneva II," he added.
Also Read
The Syrian opposition coalition had agreed to attend the London talks, saying it would focus on "these countries' understandings about Geneva II and what it should result in".
US Secretary of State John Kerry earlier said that the Syrian opposition would never agree to Assad staying in power.
"He has bombed and gassed people in his country...How can that man claim to rule under any legitimacy in the future?" Kerry had said after talks with Arab League officials in Paris.
Russia and Western nations are pushing for new talks between the Syrian regime and rebels on a negotiated solution to the conflict, which has killed more than 115,000 people since March 2011.
The National Coalition has insisted that President Assad play no role in a transitional authority, something the Syrian government has rejected.