Mr Assad is under growing international pressure, including a threat of sanctions from the Arab League, over a crackdown on anti-government protests in which the United Nations estimates more than 4,000 people have been killed.
When asked about allegations of widespread violence and torture, Mr Assad told ABC: “Who said the United Nations is a credible institution? We don’t kill our people. No government in the world [kills] its people unless it is led by a crazy person.
“Most of the people that have been killed are supporters of the government, not the vice versa.”
Syrian activists say around a quarter of the more than 4,500 deaths they have recorded in nine months of protest have been among the security forces.
The White House rejected Mr Assad’s remarks. “It is just not credible,” White House spokesman Jay Carney said.
“The world has witnessed what has happened in Syria. The United States and many, many other nations around the world who have come together to condemn the atrocious violence in Syria perpetrated by the Assad regime know exactly what’s happening and who is responsible.”
Still, Mr Assad – a 46-year-old British trained eye specialist – insisted he was not afraid of meeting the fate of other leaders deposed during the Arab Spring.
“The only thing that you could be afraid of as president (is) to lose the support of your people,” he said. “If you don’t have the support of the people you cannot be in this position,” he said.
He added: “I did my best to protect the people. You cannot feel guilty when you do your best.”