A monitoring team from the Arab League is in Syria ostensibly to verify whether the regime withdrew its forces from the streets under the terms of an agreement reached last year in Cairo.
Opposition groups and some human rights advocates accuse Damascus of hiding some of the violence from the Arab monitoring team. At least 5,000 people have been killed by Syrian forces since an uprising against Syrian President Bashar Assad began in March 2011.
White House spokesman Jay Carney said it's been more than two weeks since Damascus agreed to let the monitoring team in and more than two months since the government agreed to the Arab initiative.
He said Washington was running out of patience. If the Arab League initiative isn't implemented, then the international community needs to consider new measures.
"We believe it's past time for the Security Council to act," he said in a statement.
Russia and China have objected to a measure at the U.N. Security Council, claiming they feared another international military intervention like last year's war in Libya.
Officials and ambassadors at the United Nations had expressed concern Syria was approaching civil war.
Meanwhile, a report Wednesday in The Daily Telegraph newspaper in London reports the Syrian opposition movement is fracturing.