In a video message to the Hama provincial towns of Mharda and Sqilbiya, one of seven men armed with Kalashnikovs warned residents to expel gangs of (President Bashar al-) "Assad and shabiha (pro-regime militia) from your towns and convince them not to bomb our villages and families."
"If not, we will immediately attack the hideouts of Assad's gangs and shabiha," added the man, who identified himself as Rashid Abul Fida, head of the Al-Ansar Brigade in Hama.
Syria Observatory for Human Rights director Rami Abdel Rahman said Mharda and Sqilbiya both had pre-war populations in the tens of thousands but that most of their residents have already fled.
As the news circulated, Syria's new Greek Orthodox leader called on Christians to remain in the country despite the conflict.
Patriarch of Antioch and All the East Yuhanna X Yazigi also appealed to warring parties to renounce violence and to start a process of dialogue.
In his first press conference in Damascus since succeeding Ignatius IV Hazim, who died on December 5, he said: "We Christians are here in the country and we will stay here.
"We believe that Christ is always present in this region, which is where Christianity was born."
The patriarch sought to downplay dangers faced by Christians.
"What is happening to us is happening to others too. We are in the same situation as everyone else, Muslims and Christians, shoulder to shoulder, facing the difficulties," he said.
The patriarch called on warring parties to renounce violence "in all its forms," and to start a process of dialogue, "for our benefit, for the country, for the sake of peace (in Syria) and peace in the region."
On Monday, rebels launched an all-out assault on army positions across Hama.
There are some 1.8 million Christians in Syria. Many have remained neutral in a conflict that erupted in March 2011 and has killed an estimated more than 44,000 people. Others, fear a rise of Islamism, have taken Assad's side.
Meanwhile, there was no let-up of violence, as a car bomb in the northeast Damascus district of Qaboon killed five people and wounded dozens of others, the Britain-based Observatory said.
And Haidar al-Sumudi, a cameraman for state television was gunned down outside his Damascus home, the broadcaster said.
Elsewhere, warplanes carried out air strikes on several flashpoints, among them the eastern province of Deir Ezzor and Homs in the centre of the strife-torn country, said the Observatory.
Despite Syria's raging war, Russian Foreign Minister Sergei Lavrov said in Moscow that he believed "no one has an appetite for external intervention."
Reiterating Russia's opposition to any intervention, he added: "I even have the feeling that they are praying for Russia and China to continue blocking permission for external intervention. Because if there is such a decision, they will have to act, and no one is ready to act."
In Syria's neighbour Lebanon, German Development Minister Dirk Niebel pledged new funds to boost aid efforts for Syrian refugees streaming into the small Mediterranean country, an AFP correspondent said.
Niebel also called on Syria's neighbours to keep their borders open for people fleeing the conflict.