Russian has accused the US of applying double standards over Syria and blamed Washington for blocking a UN Security Council statement condemning a car bomb attack in Damascus.
Moscow’s statement on Friday came a day after Syrian state television reported the deaths of dozens in the blast on a busy highway in Mazraa district, damaging nearby Russian embassy buildings in the capital.
"We are disappointed that, as a result of the United States' position at the United Nations Security Council, the terrorist act in Syria was not condemned," Russian Foreign Minister Sergei Lavrov told a joint news conference after talks with China's foreign minister.
"We believe this is double standards and see in it a very dangerous tendency by our American colleagues to depart from the fundamental principle of unconditional condemnation of any terrorist act, a principle which secures the unity of the international community in the fight against terrorism."
Russia has used its status as a permanent member of the UN Security Council to protect President Bashar al-Assad from three consecutive resolutions aimed at putting pressure on him to end the nearly two-year-old conflict.
The US has called for Assad's departure but Moscow says his removal must not be a precondition for any solution of the conflict.
Besides the car bomb that struck in central Damascus on Thursday, activist groups reported three other blasts across the capital on the same day.
The Syrian Observatory for Human Rights (SOHR) said at least 90 people died in Thursday's four bombings, making it one of the bloodiest days in the city since the outbreak of a revolt against Assad.
Al Jazeera's Rula Amin reports on the blasts in Damascus
The monitoring group, quoting figures it said were compiled from hospitals and other medical sources, said at least 60 of the dead were killed in the car bomb blast in Mazraa district, near the Russian embassy and offices of Assad's ruling Baath Party.
Syrian state media put the death toll from the Mazraa bombing at 53, with more than 200 wounded.
At least 30 other people died in three co-ordinated bombings in the northeastern district of Barzeh, SOHR reported.
Both activists and officials said most of those killed were civilians, including children.
Outside the capital, more than 200 people were killed, including in the Damascus suburbs, the southern city of Deraa and the northern commercial hub of Aleppo, bringing Thursday's death to about 300 - one of the highest in a single day.
The UN says more than 70,000 people have died in Syria's conflict, which began in March, 2011.