Hours later, gunmen attacked pro-government Ikhbariya TV channel, killing three people, state media said.
The UN's human rights council is due to hear a report on Syria, including its findings on the Houla massacre.
A commission of inquiry has been investigating human rights violations in the conflict and its chairman, Paulo Pinheiro, was able to enter the country for the first time on Monday.
Earlier this month, the Geneva-based UN council called on the commission to find out who carried out last month's killings in Houla in which 108 people died.
'Winning this war'
"We live in a real state of war from all angles," President Assad told members of the cabinet who were sworn in on Tuesday.
He criticised countries that have been calling for him to stand down, saying that the West "takes and never gives and this has been proven at every stage".
He added: "We want good relations with all countries but we must know where our interests lie."