"Regional and international sides have tried to destabilize the country," Assad said in a public speech broadcast live from Damascus University.
Syria has been hit by popular protests in March, inspired by uprising in the Arab world, for an end to Assad's 11-year rule.
More than 6,000 people have been killed in the crackdown on protestors, according to the United Nations.
Syrian authorities blame foreign-backed armed groups for the violence, saying they have killed 2,000 soldiers and police.
Assad denied any policy to shoot demonstrators, according to Reuters.
"There is no cover for anyone. There are no orders for anyone to open fire on any citizen," he said.
He stressed that his priority was to restore order in Syria and that could only be achieved by "hitting terrorists with an iron fist.
"Our priority now is to regain [the] security [in] which we basked in for decades, and this can only be achieved by hitting the terrorists with an iron fist," Assad said.
We will not be lenient with those who work with outsiders against the country."
"There is no tolerance for terrorism or for those who use weapons to kill," said Assad.
Assad said he welcomed the idea of expanding the government to include "all political forces".
He, however, held out the prospect of a referendum in March on a new constitution for Syria.
The embattled leader criticized the Arab League over its position on the Syrian unrest.
"We were surprised Arabs did not stand with Syria," Assad added in his first public speech since June.
The pan-Arab body suspended Syria in November and imposed sanctions over the deadly crackdown on protestors.
The League also sent monitors to Syria to judge whether Damascus is complying with an Arab plan calling for withdrawal of troops from cities, prisoner releases and political dialogue.
Syrian opposition figures said on Monday the League mission, which began work on December 26, had failed to stop the bloodshed and was only giving Assad more time to crush his opponents.
After a review meeting in Cairo on Sunday, the Arab League said Damascus had partly implemented its pledges, but decided to keep the observer mission going for now.
Assad said Arab countries that opposed Syria were under outside pressure, which was undermining their sovereignty.
He, however, said that Syria would not "close the door" to any Arab solution that respects Syrian sovereignty.
Syrian opposition figures have called for action by the UN Security Council to halt Assad's offensive against protesters.
But the call has divided the Arab League on whether to take such a step, which in the case of Libya led to foreign military intervention that helped rebels topple Muammar Gaddafi.Russia and China have opposed any Security Council move on Syria, while Western powers hostile to Assad have so far shown little appetite for Libya-style intervention in a country that sits in a far more combustible area of the Middle East.
Reproduced with permission from OnIslam.net