Syrian forces have regained territory from the rebels by bombarding three districts of Damascus with helicopter gunships on Sunday, witnesses said, Reuters reported.
The army's elite fourth division has launched an assault on the northeastern suburb of Barzeh, and troops have been deployed in the western suburb of Mezzeh.
According to Reuters, the bombardments in Damscus showed President Bashar al-Assad's determined to regain control after a bomb killed four members of his high command last week.
"In Damascus, people continue to search desperately for safety," the International Committee of the Red Cross (ICRC) said in a statement in Geneva.
"Humanitarian needs are growing as the situation in the city worsens and as large numbers of people flee their neighborhoods in search of safe haven. The ICRC and the Syrian Arab Red Crescent have intensified their response to the situation."
The Herald Sun reported that the Syrian Observatory for Human rights has placed the overall death toll from the 16-month uprising at more than 19,000- the majority of which are civilian.
The towns of Atareb, Kafr Karmeen and Abazmo, which lie between Aleppo and the Turkish border to the west, were also reportedly bombarded by security forces, the BBC reported.
According to Reuters, the UN Security Council voted on Friday to grant a "final" 30-day extensionto the observer mission. UN Chief Ban Ki-moon has recommended changing the mission's focus to pursuing prospects for a political solution, which effectively accepts that there is no truce to monitor.
Ban said on Saturday he was "deeply distressed by the rising death toll," and he warned that the limited extension of the UN mission showed "the onus is above all on the parties, with the Syrian government in the first place, who must stop the killings."