Rights groups reported more deaths in Syria as the United States demanded that Damascus "take every possible step" to protect its diplomats after regime supporters tried to attack the US ambassador.
Security forces killed a civilian in the flashpoint central city of Homs, adding to six killed in the province on Thursday, two of them children, activists said.
The civilian was killed in the city's Al-Khalidiya neighbourhood, the Britain-based Syrian Observatory for Human Rights said.
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Security forces had also opened fire during search operations in Homs late on Thursday, killing four people, one of them a young girl, the watchdog said.
Two more civilians, one a child, were killed in Rastan, a town north of Homs which has been the scene of a massive operation by troops backed by armour for several days.
"People seriously wounded in Rastan were unable to receive medical care because of the continuing military operations," the Observatory said.
Activists say the clashes in Rastan are between the army and deserters.
Pro-democracy activists have called for demonstrations on Friday, traditionally a day for protests after the main weekly prayers, under the banner "Victory for our Syria and our Yemen. The people are stronger than any despot."
Overnight, a large explosion was heard in the Ghuta district of Homs, and the Observatory said security forces fired indiscriminately on houses in the city "until dawn."
The Local Coordination Committees (LCC) group said there was shooting in the Damascus suburb of Qabun.
The LCC, which has activists on the ground across Syria, is an active member of the Syrian National Council -- one of several opposition coalitions that has emerged since March to rally against the regime.
The official SANA news agency said 10 security personnel had been killed "by armed terrorist groups" in the Homs area, and also said a child had been killed in Idlib province in the northwest.
It said seven soldiers, including two officers, were killed in Rastan and another three members of the security forces in Tal Kalakh.
The latest deaths come after US Secretary of State Hillary Clinton demanded that Damascus "take every possible step" to protect American diplomats after supporters of President Bashar al-Assad tried to attack the US envoy on Thursday.
The attempt to storm an office in the capital where Robert Ford had just arrived came with the UN Security Council divided over whether to threaten Assad's regime with sanctions.
Opposition figure Hassan Abdelazim, whom Ford had arrived to meet, told AFP that the mob "tried to break down the door of my office, but didn't succeed" during a siege that lasted two hours.
Clinton said Washington had raised the attempted attack on Ford at "the highest levels" in Damascus and demanded that Syria "take every possible step to protect" US diplomats.
She also spoke of an "ongoing campaign of intimidation" against not only American diplomats but those from other countries.
Clinton's deputy spokesman Mark Toner said the mob tried to attack Ford and other embassy staff while they visited Abdelazim, seriously damaging US vehicles and "pelting" the visitors with tomatoes.
The Assad regime had earlier accused Washington of inciting "armed groups" into violence against its army.
Meanwhile divisions over whether to threaten sanctions against Syria for the its deadly crackdown on dissent held up UN Security Council discussions on a resolution on the crisis.
European nations and Russia have proposed rival resolutions on Syria.
Britain, France, Germany and Portugal insist that any resolution must include at least the threat of sanctions against Assad, but Russia opposes any mention of sanctions in the text.
France was to draw up a new version of the European text for possible talks on Friday.
The office of the UN High Commissioner for Human Rights in Geneva has said the death toll from the Syrian government's bloody crackdown on dissent has risen to more than 2,700 since March 15.
Sergio Pinheiro, who heads an international commission of inquiry into rights violations in Syria, told reporters in Geneva he hoped to be allowed to visit the country.
"Our hope is that the Syrian Arab Republic will cooperate and give us access to different authorities, and visit different locations," he said, but later added that "we have not yet met the Syrian authorities" to request the visit.
