Syria's President Bashar al-Assad has denied his government's forces had any role in the Houla massacre.
The BBC reports more than 100 people, many of them children, were killed in the attack in the west of the country, most knifed or shot at close range.
Mr Assad described the killings as an "ugly crime" that even "monsters" would not carry out.
Addressing parliament, he blamed "foreign meddling" for Syria's divisions.
And he again blamed "terrorists", supported by foreign powers, for fomenting discord and creating "a project of... dissent".
Mr Assad said that the country was "facing attempts to weaken Syria, breach its sovereignty".
The only way to resolve the crisis, he said, was through political dialogue. But he said he would not negotiate with those who he said did not represent the will of the Syrian people.
"We are not going to dialogue with forces co-operating with the outside the world, or forces who are engaged in terrorist actions."
The president has made few public appearances during a 15-month uprising against his rule.
UN/Arab League envoy Kofi Annan has told an Arab League meeting that the world needed to see action, not words, from the Syrian leader.
The United Nations says Syrian forces have killed more than 9000 people in a crackdown on protests which have become increasingly militarised.
Syria blames the violence on foreign-backed Islamist militants it says have killed more than 2600 soldiers and security force members.