She will also visit the Georgian capital Tbilisi next week, her spokesman said on Wednesday, although he did not specify which day.
Merkel believes, “it is completely unacceptable for the legitimacy of the democratically-elected government of Georgia... to be put into question,” he said at a news conference in Berlin.
He added that she would "make it clear" to Medvedev that the problems in the Caucasus region cannot be solved by military means, following the fighting between Russian and Georgian forces over the last week.
A ceasefire seemed to be in the offing on Wednesday as both sides agreed to a plan put forward by French president Nicolas Sarkozy.
Reports from the ground suggest villages in northern Georgia were being burned, with eyewitnesses telling the Frankfurter Allgemeine Zeitung that those responsible were Ossetian militia, while anarchistic scenes are played out in many areas with looting, kidnapping and violence.
European Union foreign ministers met in an emergency session on Wednesday to discuss sending a peace-keeping mission to Georgia, a suggestion promoted by the French government, which currently holds the European Commission presidency.
Foreign minister Frank-Walter Steinmeier warned against looking for a guilty party for the short war between Georgia and Russia over the breakaway region of South Ossetia.
“I don't want us to get lost in a long discussion about responsibility for the escalation of the last few days,” he said before entering the special meeting.
He called instead for the EU to act as an enabler for Georgia and Russia to create a lasting peace.
But the British had already decided that Russia was the aggressor, with foreign minister David Miliband calling for the EU to consider whether and if so how, its partnership with Russia should continue.
There seems to be broad agreement within the union for the French idea of sending a European peace mission to Georgia.
Georgian president Mikhail Saakashvili was supported on Wednesday by simultaneous visits from his counterparts from Poland, Latvia, Lithuania and Estonia.