A former Syrian ambassador called on President Bashar Assad to step down and halt what he called a war against the Syrian people. Nawaf al-Fares, the former Syrian ambassador to Iraq, told CNN in Qatar Sunday that Assad and his regime knew their time was up and were buying time by battling the stubborn resistance. \"They are trapped,\" said Fares, who recently defected. \"They committed crimes and they entered into a war of blood. And they are aware that they are going to pay for it. They are just buying time. Maybe they will get a chance to escape.\" Al-Fares said he did not expect the Assad regime to give up power willingly. Meanwhile, the Syrian government was denying accusations Sunday of a military massacre of anti-government rebels in the town of Tremseh. Responding to claims that more than 200 people were shot and shelled by tanks in the town Thursday, Syrian Foreign Ministry spokesman Jihad Makdissi said what happened \"was a military operation and not a massacre,\" CNN reported. He denied allegations by rebels and observers the town came under siege. \"It is quite absurd that there are some media outlets who were spreading rumors that the Syrian military dispatched 150 tanks in such a small area,\" Makdissi said. The government said the real death toll was 37, the BBC said.