"If someone believes the controlled chaos will be more useful than respect to international law and strengthening of the UN Security Council (UNSC) and UN as a whole, we can't agree with that categorically and will do everything to protect international law, UN Chapter, UNSC prerogatives," Foreign Minister Sergei Lavrov said after meeting his South African counterpart, Maite Nkoana-Mashabane.
He warned that the looming military strike against Syria announced by Washington would delay or even eliminate the prospects of holding the Geneva-II conference for solving the Syrian crisis.
U.S. President Barack Obama on Saturday announced that he has decided to take military action against Syrian government targets and sent Congress a draft resolution that authorizes a U.S. military strike over the alleged use of chemical weapons by Syrian government near Damascus on Aug. 21.
The U.S. Congress reconvenes on Sept. 9 after the summer recess.
"The longer we delay (the Geneva-II conference) and the longer those who can influence the opposition (in Syria) fail to compel it to give consent for the conference, the more civilian casualties will be there," Lavrov warned.
He described allegations that Syrian government used chemical weapons as "groundless."
"It is necessary to find out who has done that. The experts must have their say and submit all facts to the UNSC," Lavrov said, noting that the latest Group of Eight summit urged a professional investigation of any reports of chemical weapons use.
Russian President Vladimir Putin on Sunday rejected as "utter nonsense" U.S. allegations that Syrian government forces have used chemical weapons. Putin argued that it would make little sense to use the weapons as government forces are on the offensive.