13 May, 2017
The phone call comes a day after Russian official Alexander Lavrentyev said that Russia, Turkey and Iran had agreed to establish safety zones over Syria.
Elsewhere in Syria, activists say government aircraft have hit central Hama province, and there are reports of shelling and gunfire in other parts.
Rebel commander Jamil al-Saleh, in northern Hama, said that almost an hour after the deal went into effect, battles raged with government forces.
Rebels rejected the deal and said they would not recognise Iran as a guarantor of any ceasefire plan.
The Syrian military have so far not commented on the issue.
Russian Federation remains Syrian President Bashar al-Assad's most powerful ally while Turkey has backed the opposition in the conflict.
The main Syrian opposition umbrella group, the High Negotiations Committee, cautioned against attempts to "partition the country through vague meanings of what have been called".
The U.S. State Department voiced concerns about the deal, saying it was skeptical of Iran's involvement as a guarantor of the accord and Damascus' track record on previous agreements. Under a memorandum signed at the talks in Astana, the four zones are Idlib province and some parts of neighboring provinces (Aleppo, Latakia and Hama), an area north of Homs, Damascus's suburb Eastern Ghouta, and a number of provinces in southern Syria - Daraa and Al-Quneitra.
In Washington, Pentagon spokesman Captain Jeff Davis told reporters the US -led coalition in Syria had not altered its operations, but declined to comment on the de-escalation zones.
United Nations special envoy for Syria Staffan de Mistura said the agreement was important because it was being implemented by three countries who could make it work.
"We will send this list to the Russians via the Turks", the source said, speaking on condition of anonymity. It is not yet clear how the new plan would affect flight paths of coalition warplanes battling IS militants and other radical groups - and whether US warplanes would abide by a diminished airspace. The area, south of Latamneh, is expected to be part of the deal.
In answer to a question about the USA -led coalition formed in 2014 to fight the Islamic State, Lavrentiev did not mince words. "What deal?" he scoffed. Other attempts at a cease-fire in Syria have all ended in failure.
No-fly zones have been a contentious issue in the Syrian conflict, now in its seventh year; they have always been requested by rebel groups and rejected by the government.
Another question left unanswered is how the deal would affect US airstrikes targeting al-Qaida's positions in Syria.
The Foreign Ministry said regime forces would continue fighting terrorists from ISIS and al Qaeda's former affiliate in Syria, al Nusra Front, according to a statement carried by the state-run Syrian Arab News Agency.
