The chief UN military observer in Syria, Major General Robert Mood, said on Thursday that he is opposed to his 300-strong team being armed.
"I've made it quite clear, from my point of view, that to give a small observer force weapons is not a good option," Mood told a press conference in the Syrian capital.
A team of some 300 unarmed observers has been deployed to monitor an April 12 ceasefire that has never taken hold. The truce was part of a six-point peace plan drawn up by UN-Arab League envoy Kofi Annan.
The UN monitors suspended their operations in mid-June due to escalating violence.
"Our engagement with the Syrian people, the Syrian families, is based on our coming unarmed, that we are accepting and honouring the hospitality of the Syrian people," Mood said.
"The minute you come with a rifle and knock on somebody's door it's a totally different story," said the general, who urged all sides in the Syrian conflict to stop the violence and open dialogue.