Head of the Syrian regime delegation to Astana Bashar Jaafari also expressed satisfaction regarding the outcomes, stressing that Syria will continue to fight terrorism and liberate every inch of its territory.
The comments, which came during the ninth round of peace talks in Astana, also made reference to groups in Eastern Ghouta who had struggled against the Syrian regime's onslaught last month, with Lavrentyev vowing that those who did not accept forced displacement would meet the same fate.
The Guarantor States stressed the importance of implementing the De-Escalation Zones Agreement in Syria, which played a pivotal role in maintaining the cessation of hostilities, describing the Agreement as a temporary measure that can not violate the sovereignty, independence and territorial integrity of Syria. "This time round the Americans, unfortunately, have decided not to support our worldwide efforts", Lavrentyev said. According to Kazakhstan's Kazinform news service, Toma told the plenary session that Astana is the only place where the Syrian opposition wants to hold negotiations and will not go to another venue.
Delegations from Jordan and the United Nations have taken part in the talks as observers while the USA did not participate in for unknown reasons.
The flare-up between the pair may feature in talks between Iranian foreign minister Mohammad Javad Zarif and Russian counterpart Sergei Lavrov in Moscow Monday.
Iran's top diplomat had already visited Beijing and was later heading to Brussels as part of Tehran's bid to salvage the deal.
Since negotiations on Syria in Astana began at the beginning of a year ago, they have mostly focused on attempts to keep Syrian regime forces and their rebel opponents at arm's length.
Their departure means that militants from the Islamic State group fighting on the outskirts of Damascus are now the main challenge to government control over the capital and its surrounding area.