Syrian activists say that 17 civilians have been killed in the latest air strikes and shelling of a district south of Damascus.
Government forces have been closing in on Islamic State fighters in the Palestinian refugee camp of Yarmuk.
Seven children are reportedly among the dead. Al Jazeera reports more than half of the refugee camp has been destroyed.
Palestinian group Hamas has called for a truce, and the UN agency for Palestinian refugees says there could be "catastrophic consequences" if fighting around the camp continues.
"Yarmouk and its inhabitants have endured indescribable pain and suffering over years of conflict," said Pierre Krahenbuhl, UNRWA's commissioner-general.
"We are deeply concerned about the fate of thousands of civilians, including Palestine refugees, after more than a week of dramatically increased violence."
There are no hospitals in the area, no running water and "very little" electricity, the UNRWA said.
The camp has been under siege over the past few years at different times by Syrian forces, Islamic State and rebels.