The Obama administration is evaluating steps to stem the continued violence in Syria, US Secretary of State John Kerry said on Friday.

"My sense right now is that everybody in the administration and people in other parts of the world are deeply distressed by the continued violence in Syria," the top American envoy told reporters after meeting with his Canadian counterpart John Baird at the State Department.

"There's too much killing, there's too much violence and we obviously want to try to find a way forward," he said, calling the situation in Syria "very complicated and very dangerous" with a convergence of extremist groups and chemical weapons.

"So I'd just say to you that we're evaluating now; we're taking a look at steps, if any, diplomatic particularly, might be able to be taken in an effort to try to reduce that violence and deal with the situation," he added.

US President Barack Obama decided last year against arming the Syrian opposition forces in their protracted conflict with the government, despite pleas by then Secretary of State Hillary Clinton, then CIA Director David Petraeus and Defense Secretary Leon Panetta.

"We don't want any weapons to fall into the wrong hands and potentially further endanger the Syrian people, our ally, Israel, or the United States," White House spokesman Jay Carney told reporters on Friday.

"We also need to make sure that any support we are providing actually makes a difference in pressuring al-Assad," he explained. "I think it's widely viewed that a lack of weapons is not the problem in Syria right now. That's why we've focused our efforts on helping the opposition to become stronger, more cohesive and more organized."

Washington and its allies are aiming for a political transition in Syria with the departure of President Bashar al-Assad.