Lavrov met late on Monday with US Secretary of State John Kerry in Paris to exchange updates on preparations for the so-called Geneva 2 conference expected to be held next month.
Kerry has just wrapped up his eight-day trip to the Middle East and Africa to push forward the US diplomatic efforts aimed at ending the civil war that has been tearing Syria apart for more than two years.
"The [Syrian] opposition, according to John Kerry, is still working on the format of its delegation, and it will take time before we clearly understand their position and approach,” Lavrov said.
"I hope that this approach will be constructive because we [Moscow and Washington] share the opinion that this conference must be held without any preconditions,” he said, adding that the Syrian government has agreed "in principle" to send delegates to Geneva.
Many Syrian opposition groups demand President Bashar Assad’s resignation as a precondition for the talks.
The Russian minister stressed that any steps that might hamper preparations for the conference should be avoided.
"In our opinion, one such step is pushing voting on the UN resolution that accuses the Syrian government of 'all sins,' without mentioning the atrocities committed by terrorists and violations of human rights by opposition forces,” Lavrov said.
Russia's top diplomat reiterated that the list of participants in the planned conference should be expanded to include Syria’s neighbors and "key regional players” such as Iran and Saudi Arabia.
Lavrov also expressed hope that Moscow and Washington would succeed in achieving the conference's aim: to facilitate a solution to the Syrian crisis through political dialogue.
Lavrov and Kerry announced plans for the conference after their talks in Moscow on May 7. The conference is designed to be a follow-up to last year’s international meeting in Geneva that drafted a peace roadmap for Syria.
According to diplomatic sources, the conference may take place in mid-June, but both Moscow and Washington have so far avoided giving exact dates.
Kerry said on Monday that US and Russian diplomats will meet again soon to discuss progress in the preparations for the Geneva 2 conference.
"We are committed to this," Kerry told reporters after the meeting with Lavrov. "We both want to make this conference happen, if possible, together with many other countries that will join up."
More than 80,000 people have died and hundreds of thousands have fled Syria since fighting broke out between government forces and rebels in March 2011.