TEHRAN, Young Journalists Club (YJC) - Lavrov made the remarks in a meeting with Ahmad Jarba, leader of Syria's Tomorrow Movement, a Cairo-based opposition group, in Moscow on Thursday.
"Those representatives of external opposition, who got used to act solely on the basis of ultimatums and preconditions, who, to be honest, were rather promoting the ideas of their external sponsors than interests of the Syrian people, are gradually losing their influence," he said.
The top Russian diplomat also hailed a “rather sound processes in different groups of Syria’s opposition” aimed at resolving the Syria crisis, saying Moscow is actively seeking to step up negotiations between Syria’s warring sides.
"An important aspect is to establish intra-Syrian dialog, ensure ceasefire, create de-escalation zones as part of the Astana process and foster peaceful life," Lavrov said.
The international community believes that the "Syrians themselves should choose the fate of their country and for that they should agree with each other,” he added.
Jarba, for his part, underlined the importance of peace talks and praised Russia for contributing to settlement of the conflict.
“Intra-Syrian dialog is necessary between opposition and pro-government forces, between all forces, in order to find a way to resolve the crisis. And the role of Russia is very important in this regulation,” he said.
Syria’s opposition is determined to "search for joint solutions and this should be political settlement,” Jarba added.
The fight against terrorism as well as terror outfits such as Daesh and al-Qaeda, the upcoming Astana talks, the cessation of hostilities in Syria and the UN-backed Geneva discussions were among the topics discussed with Lavrov, he pointed out, Presstv reported.
US downing of Syria jet ‘outraging’
Separately on Thursday, Russian Foreign Ministry spokesperson Maria Zakharova denounced the recent US downing of a Syrian air force jet as "outraging" and a "blatant breach of norms of international law,” calling for a thorough investigation into the incident.
“We consider such actions as a conscious failure of our US partners to fulfill its obligations in the framework of the memorandum on the prevention of air incident and ensuring safety of air flights in Syria," she told a press briefing in Moscow.
On Sunday, a US Navy F/A-18 Super Hornet shot down a Syrian SU-22, which was conducting an operation against Daesh terrorists on the outskirts of the city of Raqqah.
Damascus wrote to the UN over the downing, while Moscow announced a halt to a hotline with the US meant to minimize incidents in Syrian airspace and vowed to track US-led coalition aircraft in central Syria as “targets.”
Zakharova stressed that Russia, Iran, and Turkey were making preparations for the fifth round of the Astana talks due on July 4-5.
Aid trucks reach Syrian city
In another development on Thursday, the World Food Program (WFP) said a convoy of three lorries carrying food arrived in Syria's Kurdish-dominated northeastern city of Qamishli for the first time in two years.
"This humanitarian breakthrough will allow us to increase regular support for all 250,000 people in need in Hasakah," WFP's Syria country director Jakob Kern said in a statement.
The WFP said that it could previously assist only 190,000 people by airlifts in the area.