"They (the leaders) expect that their efforts during the Minsk meeting will lead to the swift and unconditional cessation of fire by both sides," Poroshenko's office said in a statement.
Putin also confirmed that a summit was being planned for Wednesday in Minsk, but said it might not come about.
"We will be aiming for Wednesday, if by that time we are able to agree on a number of the positions that we recently have been discussing intensely," he told journalists in Sochi during a meeting with the president of Belarus, Russian news agencies reported.
Before the summit Merkel, who met Friday night in Moscow with Putin, is scheduled to meet with President Obama in Washington on Monday on a previously scheduled trip.
Merkel's visit comes as Obama considers providing modern weapons to Ukraine. Poroshenko on Saturday asked Western leaders at the Munich Security Conference to push for a quick cease-fire and defensive weapons. Merkel has opposed sending weapons to the country.
Merkel, Hollande and Putin agreed Friday during a meeting in Moscow to draft a peace plan for Ukraine based on ideas proposed by Putin and Poroshenko, but previous agreements have fallen apart even as the conflict has resulted in more than 5,300 dead.