This was despite a promise to halt the attacks on the eastern Ghouta region for 5 hours a day, starting on Tuesday.
The Britain-based Syrian Observatory for Human Rights said the fighting was fierce and broke out overnight in the rebel-held enclave on the eastern outskirts of the capital Damascus.
The French presidency said the telephone discussion between the leaders will centre on the "implementation of the resolution and on the political roadmap needed to achieve lasting peace in Syria". He said that since February 18 over 580 people are reported to have been killed and well over 1,000 injured in air and ground strikes in the Damascus, home to about 400,000 people.
It came after a nine-day campaign during which Russian-backed Syrian regime forces bombarded Eastern Ghouta, killing hundreds in one of the bloodiest episodes of the country's seven-year war.
Lowcock said a 45-truck convoy with aid for 90,000 people was ready to enter 10 besieged locations in Eastern Ghouta but had not been given permission to enter.
There has been no sign of aid deliveries to the besieged area.
Russian Federation has instead called for daily five-hour local ceasefires to establish what it calls a humanitarian corridor so aid can enter the enclave and civilians and wounded can leave.
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Lowcock reiterated the International Committee of the Red Cross' assessment that it is impossible to deliver humanitarian aid in five hours, noting that it often takes convoys with all the required clearances a day just to get through checkpoints.
Turkish troops and allied rebels have been battling the Kurdish YPG militia in Afrin since they launched Operation Olive Branch in January. The opposition's Syrian Civil Defense, also known as the White Helmets, said a total of 12 people were killed on Thursday. However, Turkey on Wednesday said that the cease-fire deal does not apply to its five-week-long offensive against YPG forces, according to Reuters.
During a news conference in Moscow Wednesday, Putin said "extremist forces" and representatives of "terrorist organizations" had prevented civilians from leaving.
Residents of eastern Ghouta say they do not trust the Russia-declared truce and the United Nations and aid agencies have criticized the unilateral arrangement, saying it gave no guarantees of safety for residents wishing to leave.
He was sharply critical of the West, and especially the United States, for fancying themselves as "champions of humanity" and saying a cease-fire depends nearly entirely on Russian Federation and Syria. As thousands of Eastern Ghouta's residents lose their homes to the bombings, the only means of survival is to dig shelters underground.
The Organisation for the Prohibition of Chemical Weapons (OPCW) has opened an investigation into the reported attack on the rebel enclave to determine whether chemical weapons were used.