The Russian president had ordered his defence minister to impose a 36-hour ceasefire on the front line, coinciding with Russian Orthodox Christmas.
Mr Zelensky has rejected this truce, insisting it is just an attempt by Moscow to put a stopper to Ukrainian advances.
He said the move would just see more equipment, ammunition, and mobilised men closer to their positions.
This, he said, would just lead to more death.
Click here to sign up for our newsletters.