"We have made a deal to co-ordinate together our efforts in order to get out of this complicated situation."
Medvedev and Sergei Lavrov, Russia's foreign minister, were the first international leaders to visit Serbia since a mass anti-Kosovo independence rally in Belgrade on Thursday.
The demonstration turned violent, resulting in a section of the US embassy being set ablaze and the death of one person.
Kosovo's ethnic Albanian-majority parliament declared independence from Serbia on February 17.
The move provoked a global diplomatic split with Serbia and its main ally Russia on one side and Kosovo's backers, including the US and most European powers, on the other.
Medvedev's visit was also marked by the signing of deal between Gazprom, the Russian state gas company, and its Serbian counterpart Srbijagas.
The two companies have formed a joint company for the construction of an underground gas reservoir and pipeline to pump Russian gas to western Europe.
In a January article titled "Gas in Exchange for Kosovo", Russian newspaper Kommersant said that Belgrade had effectively secured Russia's support on Kosovo by agreeing to the energy deals on easy terms.
Serbia argues that Kosovo's secession violates UN Security Council resolution 1244, which put the disputed province under UN administration while retaining Serbian sovereignty.