BEIRUT, Lebanon — As reports of assaults by Syrian tanks and other forces at several major rebellious areas across Syria continued for a fifth day, Russia’s leaders tried Wednesday to fend off international criticism that they were doing nothing effective to stop the bloodshed, arguing that Moscow’s efforts were far more productive and balanced than the combined Western and Arab plan.

In Moscow, Sergey V. Lavrov, the foreign minister, stressed that Russia would seek to inaugurate open negotiations between the government and the opposition. Prime Minister Vladimir V. Putin, the once and likely future president, as well as Dmitri A. Medvedev, the incumbent, weighed in, trumpeting the Kremlin’s effort as unbiased while others were acting like “a bull in a china shop,” as Mr. Putin put it.

The Russians faced a chorus of voices wondering why Syrian government tanks and artillery continued to shell civilian neighborhoods in numerous towns and cities a day after Mr. Lavrov met with President Bashar al-Assad in Damascus, the Syrian capital.

Both Britain and France noted that Mr. Assad had previously promised numerous visiting government leaders that he would end the violence, to no end.