Merkel made the remarks in a phone conversation with Russian President Vladimir Putin on Wednesday, said a spokesman for the German government.
"The German chancellor emphasized the responsibility Russia has to exert a moderating influence on pro-Russian separatists. She said the negotiated ceasefire needs to finally be respected in its entirety," Steffen Seibert said in a statement.
He said the leaders had expressed concern that violence was still being used in Ukraine every day.
The Kremlin said in a statement that during the call, initiated by the German side, the two leaders talked about the importance of withdrawal of heavy weapons by both fighting sides, Reuters reported.
"Vladimir Putin stressed the need to prevent further attacks on civilian objects by Ukrainian subdivisions in the southeast of Ukraine," the Kremlin said in its statement.
Merkel said the border between Ukraine and Russia needed to be monitored and the Organization for Security and Cooperation in Europe had a big role to play in that. She said Germany would continue to support the OSCE mission in Ukraine, adding it could play an important role in planned local elections in the regions around Donetsk and Luhansk.
The Kremlin said the two also called for a fast resolution of "the Ukrainian gas problem"