According to the Russia Today Arabic-language website, the Russian official said that the Americans should clearly explain their goal of the attack.
Earlier, Russian senator Vladimir Dzhabarov, First Deputy Chair of the Federation Council Committee on Foreign Affairs, warned such actions could lead to a major conflict and that Syria has advanced weapons, including the S-300, and that Americans should be very careful.
The Pentagon said Friday morning that the US military had bombed positions belonging to Iran-backed Resistance groups in eastern Syria at the behest of Joe Biden.
Prior to the Pentagon's confirmation, Reuters quoted two informed officials as saying that the United States had attacked positions allegedly belonging to forces allied with Iran in Syria.
According to the report, the officials, who wanted to remain anonymous, said that the attack was authorized by the new US President. A US official claimed it was in response to recent attacks on US positions in Iraqi city of Erbil.