The White House said Monday that President Barack Obama had so far made no decision on whether to launch air strikes on Islamic State militants in Syria.

"The president has not made any decision to conduct military action in Syria," White House spokesman Josh Earnest said, amid rising expectations of US action following American attacks against the jihadist group in Iraq.

Earnest addressed reports that the Pentagon has been preparing options for US military action in Syria, saying it was the job of the US military headquarters to plan for all kinds of scenarios.

"The president has not made any decision to order military action in Syria," Earnest said, before the president was due to meet Defense Secretary Chuck Hagel on issues including the situation in Iraq and the threat from IS.

Earnest did not directly respond to a comment by President Bashar al-Assad's regime in Syria that it was willing to work with the United States to take on "terrorism" inside Syria, in a reference to IS forces opposed by both Washington and Damascus.

Syrian Foreign Minister Walid Muallem was also quoted as saying that any US air strikes would require coordination with the government in Damascus or they would be considered a violation of its sovereignty.

Washington has repeatedly demanded Assad leave power and accused him of gross violations of human rights in a civil war that has killed at least 190,000 people.

Earnest appeared to hint that if Obama were to decide to launch attacks on Syrian territory, he would not feel the need to inform the Damascus government.

"The president has already demonstrated a willingness, where necessary ... to use military force to protect the American people, regardless of borders.

"This is evident from the president ordering the mission to go and get Osama bin Laden.

"The United States was not invited in by the Pakistani government. That was a decision that the president made to go and get Osama bin Laden."