John Kerry has suggested preventing the fall of the Syrian border town Kobani is not a strategic US objective.
Islamic State appeared close to taking Kobani, with militants raising the group's flag over eastern parts of the town on Monday.
Although US-led air strikes have helped halt the group's advance, intense clashes between Kurdish troops and IS fighters continue.
Mr Kerry said while the US was "deeply concerned for the people of Kobani" and had conducted more strikes in the region as a result, it had to focus on the bigger strategic objectives.
"As horrific as it is to watch in real time what is happening in Kobani ... you have to step back and understand the strategic objective," the Secretary of State told reporters alongside UK Foreign Secretary Philip Hammond.
Kerry added: "Notwithstanding the crisis in Kobani, the original targets of our efforts have been the command and control centers, the infrastructure.
"We are trying to deprive the (Islamic State) of the overall ability to wage this, not just in Kobani but throughout Syria and into Iraq."
Satellite images have revealed the destruction in and around the town of Kobani, on the Syrian border.
Members of a prominent motorcycle gang from Holland have reportedly joined forces with Kurdish troops in Iraq to fight IS militants.
The sister of a UK journalist being held by Islamic State militants has appealed for his captors to reopen dialogue aimed at freeing him.