BEIRUT — As Syrian forces struggled to drive rebels from the country’s largest city, the regime’s key ally Iran tried Thursday to start an alternative political process to address the crisis.

Iran gathered an array of nations ranging from strong supporters of Damascus to far-flung nations a world away from the Syrian civil war.

The one-day forum is unlikely to result in any international consensus, but it shows Iran’s resolve to stand by President Bashar Assad as his forces try to crush the 17-month-old uprising.

On Thursday, Syrian rebels said they were low on ammunition but still managed to put up resistance against a regime ground offensive in the city of Aleppo, a center of fighting for more than two weeks.

Tehran billed Thursday’s conference as a way to focus on dialogue — an alternative to Western-led initiatives that call for Assad to give up power.

Iran has said in the past that the Syrian regime’s critics fail to take into account violence by the rebels.

“Iran is against the killing of unarmed people and citizens by any side,” Iranian Foreign Minister Ali Akbar Salehi said at the gathering.

He also warned that sending weapons to the opposition will only fuel the crisis, and he accused rebels of using civilians as “human shields.”

Syrian rebels last week intercepted a bus carrying 48 Iranians in a Damascus suburb and seized them. Rebels claimed the men are military personnel, including some members of Iran’s powerful Revolutionary Guard, who were on a “reconnaissance mission” to help Assad’s crackdown.

Iran, however, says the 48 were pilgrims visiting a Shiite shrine in Damascus. Salehi said Wednesday that some of the pilgrims are retired members of the army and Revolutionary Guard.

The overwhelmingly Sunni Muslim rebels have also seized 11 Lebanese Shiite pilgrims who have been held in northern Syria since May.

Salehi said some 30 countries attended the meeting, including Russia and China, as well as far-off Benin, Cuba and Mauritania. The meeting was called at short notice, and most countries were represented at the ambassador level.

Russia in the past has urged the West to allow Tehran to take part in international discussions on how to settle the Syrian crisis, arguing that the Islamic republic could play an important role. Moscow has been the main protector and ally of Assad’s regime, shielding it from U.N. sanctions over its brutal crackdown on an uprising that has evolved into a full-blown civil war.

The U.S. dismissed the Iranian gathering.

“We think the Iranian behavior in Syria is destructive,” State Department spokesman Patrick Ventrell said. “It’s just hard for us to imagine that after putting so much effort into keeping Assad in power ... how they can be a constructive actor in facilitating a political solution to the crisis.”

On Thursday, government troops and rebels clashed in opposition bastions of Aleppo, a city of 3 million people.

The state news agency claimed Wednesday that Assad’s force had regained control of the Salaheddine neighborhood, the main rebel area in Aleppo. But activists said rebels were still putting up a fight there on Thursday.

“The battle is still going on in the streets of Salaheddine and in other neighborhoods in Allepo,” rebel spokesman Abdel Azziz Salameh told The Associated Press. “Our fighters have a shortage of ammunition but they have not withdrawn.”

The regime has been trying to drive rebels out of Aleppo for two weeks. But the blistering attacks on rebel positions from the ground and the air appear to be only slowly chipping away at the opposition’s grip on its strongholds.

Aleppo-based activist Mohammad Saeed said troops were using warplanes and tanks to shell the towns of Hreitan and Tel Rifat north of Aleppo, from where most of the rebels converged on the city.

“They are trying to cut the main lines from Tel Rifat to Aleppo,” Saeed said.

Aleppo holds great symbolic and strategic importance. Some 25 miles (40 kilometers) from the Turkish border, it has been a pillar of regime support during the uprising. An opposition victory there would allow easier access for weapons and fighters from Turkey, where many rebels are based.

Syria’s close ties to Iran and the Islamic militant group Hezbollah in Lebanon mean that the conflict has the potential to draw in the country’s neighbors.

On Thursday, Lebanese officials arrested Michel Samaha, a former Lebanese minister and parliament member, who is one of the most ardent Lebanese supporters of the Syrian regime.

Samaha often appeared on local TV stations as an analyst and spoke out in favor of the regime. His wife, Gladys, told local media that security agents kicked in the front door early Thursday and pulled Samaha from his bed. She called his arrest a purely political detention because of his political position.

But Lebanese officials said only that he was arrested for “security” reasons. They spoke on condition of anonymity because they were not allowed to speak to the media.

Also Thursday, Assad appointed a new prime minister to replace the one who defected to neighboring Jordan this week. State-run news agency SANA said he appointed Health Minister Wael Nader al-Halqi, a Sunni member of the ruling Baath party from the southern province of Daraa, the birthplace of the revolt.  

Al-Halqi replaces Riad Hijab, whose defection was a humiliating blow to the regime. Like nearly all prominent defectors so far, Hijab is a member of Syria’s majority Sunnis — the Muslim sect which forms the bedrock of the uprising.

Still, power remains closely held within Assad’s inner circle and the most significant leadership is dominated by members of the ruling elite’s minority Alawite sect, an offshoot of Shiite Islam.