According to the initial announcement by Ukraine's president's office, the two leaders spoke on the phone and agreed on a "permanent ceasefire" in Donbass.
"Their conversation resulted in agreement on a permanent ceasefire in the Donbass region," Poroshenko's office said. "They reached a mutual understanding on steps leading to peace."
However, the statement was later changed to say: "Their conversation resulted in agreement on a process for ceasing fire in the Donbass region."
In a separate statement, the Kremlin said a phone conversation had taken place on Wednesday between the two presidents in which their points of view had "coincided significantly" on possible ways to end the crisis.
Mr Putin's spokesman, Dmitry Peskov, told Russian news agency Ria-Novosti: "Putin and Poroshenko did not agree a ceasefire in Ukraine because Russia is not party to the conflict, they only discussed how to settle the conflict."
More than 2,600 civilians and fighters have been killed and more than a million people have fled their homes since fighting erupted in eastern Ukraine in April, when pro-Russian separatists there declared independence.
Russia has denied accusations by the West and the Ukrainian government that it is sending troops and military equipment over the border to support the separatists, who recently gained the upper hand against government forces.
The presidents of Russia and Ukraine met in person last week in Minsk, but no breakthrough was achieved then.
This is a second announcement of a ceasefire in Donbass. The Ukrainian government called a unilateral seven-day ceasefire on 20 June. However, rebel fighters continued to attack government forces.