According to the report, she said this at a press conference with Iraqi Prime Minister Haider Jawad Kadhim Al-Abadi in Berlin.
"We do not know whether the talks in Moscow will be long or short, or the last ones," she said.
The chancellor also promised to make every effort to stop the bloodshed in Ukraine.
"In addition, it is unclear whether an agreement on a ceasefire in the conflict zone will be reached during the negotiations," Merkel said.
Meanwhile, French President François Hollande said that such an agreement should be the first step to resolving the Ukrainian crisis.
"But this is not enough. We need a comprehensive agreement," Hollande said.
As reported earlier, on Friday Merkel and Hollande will visit Moscow to discuss the resolution of the conflict in Ukraine with Russian President Vladimir Putin.