"It's necessary to start detailed, substantial dialogue," Putin told reporters today. "This will guarantee success."
Putin made his comments after Ukraine's new Western-backed President Petro Poroshenko said he was prepared to talk to those separatists not implicated in "murder and torture" as he laid out the details of a new peace plan.
The Kremlin chief spoke to reporters after laying a wreath at the Tomb of the Unknown Soldier to commemorate the anniversary of the start of World War II in the Soviet Union in 1941 when Russia and Ukraine battled against Nazi Germany together.
"Russia will certainly support these intentions. But at the end of the day, the most important thing is a political process. It's important for dialogue between all warring parties to originate on the basis of this peace plan," Putin said in televised remarks.
For the peace plan to work, Russian speakers in the separatist east should feel they are "an inalienable part" of Ukraine and know that their rights are guaranteed by the constitution, Putin said.
Poroshenko announced a unilateral week-long ceasefire on Friday along with the peace plan, which Putin said at the time did not go far enough because it lacked an invitation to separatists to sit down at the negotiating table.
Today, Putin said the fighting was continuing despite the ceasefire.
"Military operations have not stopped," he said. "I can't say who is doing this - whether this is a regular army or whether these are the armed units of some right forces but this is happening."
Putin issued apparently conflicting signals yesterday, first putting troops on full combat alert, then offering a measured endorsement of Poroshenko's peace plan.
But the Kremlin strongman said the peace plan would not be viable unless the authorities begin genuine talks with the rebels.