KABUL, Afghanistan - Standing before power brokers and tribal elite Wednesday morning, Afghan President Hamid Karzai was about 10 minutes into a nationally televised appeal for reconciliation with the Taliban when the insurgents responded with a rocket that slammed into a nearby hillside.

"Don't worry," Karzai coolly told the gathering before the attack escalated. "We've heard these kinds of things before."

Assailants with suicide vests, rockets, and machine guns then tried unsuccessfully to breach defenses set up for the cavernous meeting tent at Kabul's Polytechnic University campus, where a national peace "jirga," or assembly, was called by Karzai.

Even with thousands of police and troops protecting the city, the attackers fought for more than 45 minutes.

Amid the gunfire and explosions, Karzai and the 1,600 Afghan delegates to the three-day assembly carried on with the opening ceremonies.

"The president was really brave," said Shukria Barakzai, an independent lawmaker attending the gathering. "Usually when there is a threat or an attack he leaves the hall, and this time he said, 'We don't care if there are rockets or missiles.' "

The Taliban said the attack was a message that the gathering would not draw it into talks with Karzai and the U.S.-led international military coalition that backs him. The insurgents are demanding the immediate departure of foreign troops as a condition of peace talks.

"Make peace with me and there will be no need for foreigners here," Karzai said in a direct appeal to the Taliban as the attack unfolded.

"My dear Taliban, you are welcome in your own soil. Do not hurt this country, and don't destroy or kill yourselves," he said, emphasizing that more fighting would only prevent the withdrawal of international forces.

The rare gathering is meant to boost the president's nascent efforts to launch substantive peace talks with Afghan insurgents.

By Friday, Karzai expects the handpicked assembly delegates to give him a mandate to pursue negotiations to end the nearly nine-year-old war, which has caused the deaths of at least 10,000 Afghan civilians, thousands of Afghan soldiers, and nearly 1,800 members of the international military coalition, more than 1,000 of them Americans.

"They cannot stop the jirga," said Safiya Sidiqi, a lawmaker from eastern Afghanistan's Nangarhar province.

However, Sidiqi said there were already indications in the gathering of troubling fissures as some warlords staked out hard-line positions against offering the Taliban any significant concessions.

Karzai has said he is willing to talk to any Taliban leaders who distance themselves from al-Qaeda, renounce violence, and accept the country's constitution.

The Afghan president already is pursuing talks with Gulbuddin Hekmatyar, a warlord and Taliban ally who had a close relationship with Pakistan and the CIA during the 1980s war against the Soviet occupation and then earned notoriety by shelling Kabul during the 1990s civil war.

The Taliban attack on Wednesday's gathering, however, made it clear that plenty of fighters aren't willing to give up.

Security forces converged on a house a mile or two from the heavily secured meeting tent where they battled at least two men with suicide vests, said Zemiri Bashary, a spokesman for the Interior Ministry.

Bashary said the men had used women's burqas, an all-enveloping robe and veil, to sneak into the area. Two of the attackers were killed and a third was arrested. Three civilians, but no delegates, were wounded.

The Obama administration supports overtures to rank-and-file insurgents but is skeptical of a major political initiative with Taliban leaders until extremist forces are weakened on the battlefield. NATO troops are preparing for a big offensive this summer in the Taliban heartland of Kandahar province.