But Europe's dependence on Russian oil and gas effectively ruled out stronger sanctions.
"I think we found an excellent compromise (by) not going back to business as usual, but still making clear that we want to maintain contact with Russia," said German Chancellor Angela Merkel.
At a four-hour meeting, the leaders tasked EU bureaucrats to study alternative energy sources to reverse growing dependence on Russia, which currently supplies a third of the EU's oil and 40 percent of its natural gas.
Earlier, Russia warned the West against supporting Georgia's leadership, suggesting that the United States carried weapons as well as aid to the ex-Soviet republic and calling for an arms embargo until the Georgian government falls.
French President Nicolas Sarkozy said he plans to travel to Moscow on Sept. 8 for talks with the Russian leadership. A cease-fire he brokered to end fighting between Russian and Georgia calls for forces to be withdrawn to their positions before the war.
"If instead of choosing their national interests and the interests of the Georgian people, the United States and its allies choose the Saakashvili regime, this will be a mistake of truly historic proportions," Russian Foreign Minister Sergey Lavrov said.
Hours after Lavrov's comments, the spokesman for the Foreign Ministry suggested U.S. ships that carried humanitarian aid to Georgia's Black Sea coast following last month's war may also have delivered weapons.
Without naming a specific country, Foreign Ministry spokesman Andrei Nesterenko said there were "suppositions" that the cargo of military ships bringing aid to Georgia may also have included "military components that will be used for the rearmament" of Georgia's military. He provided no evidence, but said such suspicions were a reason for Russia's call for an arms embargo.
Lavrov reserved particular criticism for the United States, which has trained Georgian troops, saying such aid had failed to give Washington sufficient leverage to restrain the Georgian government. Instead, he said, "It encouraged the irresponsible and unpredictable regime in its gambles."
Neither the State Department nor the Pentagon had immediate comment.
Human Rights Watch said Monday that Georgia - as well as Russia - dropped cluster bombs during the conflict. The rights group said Georgia's government has admitted it, while Russia continues with denials.
"These indiscriminate attacks violate international humanitarian law," said Bonnie Docherty, arms division researcher at the New York-based body, who said the casualty toll in only four Georgia villages from cluster bombs and their leftover duds was 14 dead and dozens wounded.
The revelation could provide fuel for Russia, which has traded allegations with Georgia over controversial weapon usage, human rights violations and disinformation.
Huge crowds of Georgians surged into the streets of the capital, Tbilisi, to demonstrate against Russia while others gathered at a Russian checkpoint where soldiers are guarding the "security zone" Moscow claimed for itself after last month's war.
Large demonstrations also took place in Poti, the Black Sea port city where Russian forces have a checkpoint on the outskirts, and in Gori, which was bombed and then occupied by Russian forces.
Several hundred people marched from Gori to the Russian checkpoint at Karaleti, about four miles north, where soldiers watched impassively but a tank turret swiveled ominously from behind an earthen fortification.
No figures for total turnout nationwide were immediately available, but the television station Rustavi-2 said more than 1 million people participated in the demonstrations that also included the cities of Kutaisi and Zugdidi.
The crowd that jammed Tbilisi's main avenue alone appeared to have at least 100,000 people. The Tbilisi demonstration started with people holding hands to form "human chains" in an echo of the so-called Baltic Chain of 1989 in which residents of then-Soviet Lithuania, Latvia and Estonia stretched the length of their homelands to protest Soviet occupation.
A 60-year-old demonstrator, Tengiz Kuparadze, said he was in Lithuania for that event.
"Now, Lithuania has become free; it is a member of the European Union and reliably protected against Russia. Georgia will fight for this, and will win," he said.
On Aug. 7, Georgian forces attacked South Ossetia, hoping to retake the province, which broke away from Georgia in the early 1990s. Russian forces repelled the offensive and pushed into Georgia. Both sides signed a cease-fire deal in mid-August, but Russia has ignored its requirement for all forces to return to prewar positions.
Moscow has insisted the cease-fire accord lets it run checkpoints in security zones of up to 4 miles into Georgian territory.
