US Secretary of State Condoleezza Rice has said she will travel to the Middle East to try to find an "endurable peace" to the conflict in Lebanon.
Rice said Hezbollah was "the source of the problem"
She dismissed calls for an immediate ceasefire between Israel and Hezbollah.
It "would be a false promise if it simply returns us to the status quo", she said, adding that the root causes of the violence needed to be addressed.
Her comments came as Israel called up thousands of reserve troops, amid speculation of a large-scale incursion.
The crisis was triggered by the capture of two Israeli soldiers by Hezbollah militants on 12 July.
Ms Rice told reporters at the state department in Washington that Hezbollah was guilty of "outrageous provocation" and "the source of the problem".
She ruled out a ceasefire that "acknowledges and freezes" the pro-conflict status quo.
"We will be back here in six months again... or in a year... trying to get another ceasefire because Hezbollah would have decided... yet again to use southern Lebanon as a sanctuary to fire against Israel," she said.