Earlier on Thursday, sponsors of the resolution had urged Russia not to veto the "purely humanitarian" measure.
Speaking before a UN Security Council meeting on Syria, ambassadors of sponsors Belgium, Kuwait and Germany warned that the conflict could become the century's worst humanitarian crisis if the fighting persisted.
"The Council cannot, must not, let that happen," they said.
The resolution, which was put to a vote in the Security Council, said "all parties shall immediately cease hostilities to avoid a further deterioration of the already catastrophic humanitarian situation in Idlib Governorate, beginning at noon Damascus time on 21 September 2019".
Russia backs the Syrian regime of Bashar al-Assad, which has been conducting a bloody four-month-long campaign to take Idlib province.
On Wednesday, UN Secretary-General Antonio Guterres joined the head of the International Committee of the Red Cross Peter Maurer in appealing for an end to air and artillery bombardments of Idlib, citing the devastating impact on civilians.
Belgium, Kuwait and Germany have taken a leadership role in the council in following the humanitarian situation in Syria, a role known in UN parlance as "penholders."
"As co-penholders of the humanitarian file for Syria in the Council, we would like to call upon all member states to vote in favor of our resolution," they said.
"Our draft resolution the Council will vote on today is a purely humanitarian one," they said, noting that half a million people have been displaced since the Idlib offensive began four months ago.
Agencies contributed to this report.
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