Interior Minister Gemayel, a strong critic of Syria, died in hospital earlier in the day after gunmen opened fire on his car in a suburb of the Lebanon's capital, Beirut.
"Such actions will only delay the time when the domestic situation in the country can be stabilized," Mikhail Kamynin said.
Pierre Gemayel, the son of former president Amin Gemayel, was a member of the Christian Phalange party. His murder is likely to heighten the political standoff between the country's anti-Syrian majority and the pro-Damascus opposition led by Islamist group Hizbollah.
Gemayel was the fifth high-ranking Lebanese figure to be assassinated in the last two years, in a series of murders including that of former prime minister Rafik Hariri.
Saad Hariri, son of Rafik Hariri and the majority leader in the Lebanese parliament, has blamed Damascus for alleged involvement in the latest killing.
The Russian Foreign Ministry offered condolences to the family of Pierre Gemayel and his relatives, and expressed hopes that "Lebanese law enforcement agencies will conduct a full investigation" into his killing.
