Pakistan's new president said he was trying to convince his country to support the war against Islamic extremists, after a group that claimed responsibility for the Marriott Hotel bombing threatened more attacks.

The attack in the capital Islamabad and the new threats underscored the danger Islamist militants pose to Pakistan, where Al Qaeda and Taliban fighters have established bases in tribal regions along the border with Afghanistan.

The U.S. has pushed Pakistan to crack down on the northwest bases, even launching its own attacks, but those American strikes have outraged a population already unhappy with Pakistan's alliance with the United States.

Pakistani President Asif Ali Zardari told reporters Wednesday on the sidelines of the U.N. General Assembly in New York that international support for Pakistani anti-terror efforts was important, but that unilateral U.S. strikes undermined efforts to win "hearts and minds."

"There is the physical (security) dimension, there is the economic side," Zardari said, according to the state-run Associated Press of Pakistan. "The idea is to increase acceptance of the fight inside Pakistan and outside Pakistan, and we are striving to improve on this idea."

Meanwhile, in a cell phone message to reporters, the little known group calling itself "Fedayeen al-Islam" — "Islam commandos" — called on Pakistan to stop cooperating with the United States and referred to the owner of the Marriott in Islamabad by name.

"All those who will facilitate Americans and NATO crusaders like (owner Sadruddin) Haswani, they will keep on receiving the blows," said the message in English.

It was impossible to verify the identity of the group or say whether it was in a position to make good on the threat. Pakistani officials were not immediately available for comment.

The group in an earlier message claimed responsibility for Saturday's truck bombing that killed 53 people and wounded more than 270.

Little or nothing is known about the group. Pakistani officials suspect Al Qaeda or Taliban militants carried out the bombing.

Concerned about the possibility of further attacks, the U.S. State Department has announced it is prohibiting all American government personnel from staying at or even visiting major hotels in Islamabad and the key cities of Karachi and Peshawar, and told them to stay away from restaurants as well.

In addition, a notice from the U.S. Embassy in Islamabad urged American citizens working or visiting there to take similar precautions, while announcing that visa and other routine consular services were temporarily suspended as of Thursday. Emergency assistance to U.S. citizens will continue to be available.

The U.S. has stepped up attacks on suspected militants in the frontier area, mostly by missiles fired from unmanned drones operating from Afghanistan. The incursions — especially a ground raid into South Waziristan by American commandos Sept. 3 — have angered many Pakistanis.

On Wednesday, Pakistan's army said it had found the wreckage of a suspected surveillance drone in South Waziristan, but denied claims by Pakistani intelligence officials that troops and local people shot down the aircraft.

The army statement said security forces recovered the drone, but it did not say anything about the plane's origin. It said a technical problem appeared to have caused the plane to crash and it was investigating.

The U.S.-led coalition in Afghanistan said one of its drones went down Tuesday in the Afghan province of Paktika, bordering South Waziristan. But it said coalition forces retrieved the plane and no others were missing. The CIA also operates drones in the region.