The U.N. had denounced the attacks in a statement that appeared to hold President Bashar Assad's regime responsible, and the White House called the violence acts of "unspeakable and inhuman brutality." Syria blames armed "terrorist groups."
"Children, women and other innocent people were killed in their homes and this is not what the Syrian army does," Makdissi said. "The method of killing was brutal."
The bloodshed is yet another blow to the international peace plan brokered by Annan and cast a pall over his coming visit to check on the plan's progress. The cease-fire between forces loyal to the regime of Assad and rebels seeking to topple it was supposed to start on April 12 but has never really taken hold, with new killings every day.
The U.N. put the death toll weeks ago at more than 9,000. Hundreds have been killed since.
Also Sunday, government troops shelled residential areas in central Syria.
The shelling hit neighborhoods in the central city of Hama and the rebel-held town of Rastan north of Homs, the Local Coordination Committees and the Britain-based Syrian Observatory for Human Rights said.
The two groups also reported clashes between troops and rebels in Hama, in the Damascus suburb of Harasta and in the capital's central Midan district. They said a bomb struck a security vehicle in the capital's upscale district of Mazzeh near a military airport, according to the LCC.
The Observatory said the vehicle bombing caused casualties but did not have other details on the dead or wounded from the day's violence.
A video posted online by activists showed thick black smoke billowing from what it said was Mazzeh.
Damascus is tightly controlled by regime forces but has been hit by a wave of blasts over recent months that claimed the lives of scores of people. Most of the blasts have targeted Syrian security agencies.