The United States on Tuesday accused Syrian President Bashar al-Assad of doing everything but what he needs to do, saying he was not meeting the commitments his country made to the Arab League.

In response to Assad's fourth speech earlier in the day since the eruption of unrest in Syria in mid-March, State Department spokeswoman Victoria Nuland said the president seemed to " aggressively" deny any responsibility for the violence in his country.

"It's interesting, throughout the course of this speech, Assad manages to blame a foreign conspiracy that's so vast with regard to the situation in Syria that it now includes the Arab League, most of the Syrian opposition, the entire international community, " she said at a regular news briefing.

"He's doing everything but what he needs to do, which is to meet the commitments that Syria made to the Arab League to end the violence, to pull tanks and heavy weapons out of cities, to allow journalists in, to release political prisoners, and to allow a real space for political dialogue to take place," she added.

Addressing supporters at Damascus University, Assad vowed to fight the "terrorists" in his country with an "iron fist," saying they are working to pave the way for foreign interventions.

Saying he would not give up responsibility so long as he still has the support of his people, the embattled president pledged that his country would not close door to any Arab solution that respects the Syrian sovereignty and the independence of the country's decision. He added that he was the one to suggest the need for Arab monitors who started their mission on Dec. 26 to find out the truth in Syria.

Nuland dismissed Assad's speech as an effort to "deflect the attention of his own people from the real problems," and reiterated the U.S. call for him to step down.