United Nations Envoy Kofi Annan is urging the rest of the world to step up pressure on Syria.
At least 78 people were killed Wednesday, including women and children according to the U.N.
Witnesses say government-backed forces went on a rampage, murdering and burning citizens.
"The regime-sponsored violence that we witnessed again in Hama yesterday is simply unconscionable," U.S. Secretary of State Hillary Clinton said.
U.N. Secretary-General Ban Ki-Moon also said U.N. monitors were shot at as they tried to get to the scene of the latest attack.
Syrian President Assad al-Bashar continues to deny any attacks against anti-government protestors.