Poroshenko is scheduled to see Putin in the Belarussian capital Minsk on Aug. 26 at a meeting that will also include top leaders of the European Union and of the Russian-led Customs Union.
Though he did not mention Putin by name, Poroshenko was quoted by his website as saying that the Ukrainian side "would call for the (rebel) fighters to be withdrawn from Ukraine."
"I am sure we will succeed in this," he said.
Poroshenko's pro-Western leadership accuses Russia of orchestrating separatist rebellions in Ukraine, in which more than 2,000 people have been killed, and of arming the rebels. Moscow denies this.
Saying he was going into the talks with the intention of trying to find a peaceful end to the conflict, he added: "In order to have solid positions in peace negotiations, it is necessary to be strong, to have the unity of the people, a strong country, a strong army.
"We are capable of defending our sovereignty, out independence and our territorial integrity. Today we are fighting for the independence of Ukraine. We together will win for sure," he said.
Next Tuesday's meeting will be the first between Poroshenko and Putin since a frosty encounter in June in Normandy, France, during World War Two D-Day commemorations.
The meeting has raised prospects of a breakthrough to end months of confrontation between Kiev and Moscow over the future direction of Ukraine whose leadership has set out on a road of integration into mainstream Europe to the dismay of its former Soviet ruler.
The confrontation has provoked the worst crisis between Russia and the West - which backs Kiev's pro-Europe course and its accusations of Russian involvement in separatist fighting - since the end of the Cold War.
