Syrian government forces stormed restive districts of a central city on Wednesday, firing mortars and deploying snipers in an assault that killed at least one person, activists said.
The assault began Tuesday night, according to the Local Coordination Committees, an umbrella group of activists and opposition members.
Shells slammed into several districts around Hama's Bab Qebli area, the group said.
One person was killed by sniper fire, according to the LCC and another opposition group, the British-based Syrian Observatory for Human Rights.
Meanwhile in Moscow, Russia's foreign minister said Wednesday that his country will stonewall any U.N. sanctions on Syria and will push for a quick start of talks between the Syrian government and the country's opposition.
Foreign Minister Sergey Lavrov said Moscow would block any attempts to get U.N. approval for sanctions against Syria that have been imposed by other nations, saying that such a move would be "unfair and counterproductive."
The U.S., the European Union, the Arab League and Turkey all have introduced sanctions against Damascus in response to Syrian President Bashar Assad's violent crackdown on opponents.
The uprising has left more than 5,400 people dead, according to U.N. estimates.
The U.N. Security Council has been unable to agree on a resolution since the violence began in March because of strong opposition from Russia and China.
Other Arab states have been stepping up pressure on Syria to end 10 months of bloodshed. Syrian Foreign Minister Walid al-Moallem signaled Tuesday that the crackdown will continue, adding that Syria will solve its own problems.
Mr. al-Moallem's televised news conference came amid signs that the current Arab strategy to solve the crisis was collapsing.
Gulf Arab countries on Tuesday said they were pulling their observers from an Arab League mission in Syria and urged the U.N. Security Council to take all "necessary measures" to force the country to implement a League peace plan announced Sunday to create a national unity government in two months.
Damascus has rejected the plan as a violation of national sovereignty.
Mr. al-Moallem brushed off the threat of referring the issue to the Security Council - a move that could lead to tougher sanctions - rather than trying to resolve it regionally.
The prospect of U.N. involvement has raised fears in Syria that an international intervention could be next.
Mr. Lavrov on Wednesday said Russia's own draft of a Security Council resolution on the violence in Syria remains on the table, and that Moscow was open for any "constructive proposals."
Western diplomats said the Russian proposal falls short of their demand for a strong condemnation of the Syrian regime's crackdown on civilians.
But Mr. Lavrov reaffirmed that any U.N. resolution must say clearly it "couldn't be interpreted to justify any foreign military interference in the Syrian crisis."