Thousands of air strikes and missiles by Russia killed at least 1,733 civilians in Syria since September 30, London-based Syrian Observatory for Human Rights (SOHR) documented in its latest report.
The organisation said on Wednesday that the assaults killed 4,408 people in total in several provinces of Syria.
The civilian death toll included 429 children and 250 women.
An agreement aimed to cease hostilities and six-year of conflict in the country was agreed by the United States and Russia in February.
However, the cessation of hostilities deal does not include DAESH, the Al Qaeda-linked Nusra Front and any other militias designated as terrorist group by the UN Security Council. Both the US and Russia continue to target those terrorist groups with air strikes in Syria.
The report came shortly after the monitoring group stated that unidentified war planes blamed to be Russian attacked six Syrian towns in the western part of Aleppo province despite cessation of hostilities deal.
A spokesman for the Syria's opposition High Negotiations Community (HNC) said that some terms of cessation were heavily influenced by Russia and were obscured. He said opposition fears that Russia would use the terms agreed on by both sides and taking it as an excuse to target Free Syrian Army, claiming to target terrorist factions.
"We are studying this truce and we are worried about the obscure points. There is no objection to the truce if it is implemented precisely, without Russia taking it as an excuse to target the moderate revolutionary factions," Muslet said.
The cessation terms were also promised to be applied by the regime leader Assad on condition terrorists did not use a lull in fighting to their advantage and that countries backing opposition forces halted support for them.
Syrian regime forces have been supported by Russian air strikes since September 2015, when the regime leader Bashar al Assad asked Russian President Vladimir Putin for help in his offensive against DAESH terrorist organisation.
However, Russian officials later admitted bombing non-DAESH, opposition held areas where civilians live, after it was blamed by the US for using DAESH as an excuse to preserve the Syrian regime.