Islamist hardliners in Somalia have vowed more war against the country's new government Thursday, as suspected insurgents targeted Mogadishu's main seaport with mortars, Radio Garowe reports.

Muktar Robow "Abu Mansur," spokesman for al Shabaab, told a press conference at the former parliament hall in Baidoa that new Somali President Sheikh Sharif Ahmed is "far from the Mujahideen."

"The Mujahideen have won and will continue the war against foreign troops in the country [Somalia] and the ones who will be coming," Abu Mansur said, while referring to a 3,500-strong African Union peacekeeping contingent serving in Mogadishu known as AMISOM.

He rejected widespread media reports that he traveled to Mogadishu earlier this week to meet with President Sheikh Sharif in person, saying that such reports spread by people who want to divide al Shabaab.

"I did not meet with Sheikh Sharif nor will I meet with him and I urge the Mujahideen to unite and to fight the new government," Abu Mansur declared.

Al Shabaab's spokesman expressed strong words for a group of self-appointed Somali Muslim scholars who have been leading efforts to mediate among Islamist factions.

He accused the scholars, led by Sheikh Bashir Ahmed Salad, of being "allies" of new President Sheikh Sharif, while warning the scholars not to label al Shabaab as "Khawarij," a reference to an Islamic cult that spearheaded bloodshed among Muslims centuries ago.

Abu Mansur also called on Somali government forces in Bakool region to "surrender and become citizens" or face war. READ: Tensions in SW Somalia between govt forces, al Shabaab

He said that a ship transporting new weapons for AMISOM peacekeepers is docked at Mogadishu's main port, giving al Shabaab enough reason to target the port with mortar bombs.

But AMISOM spokesman Maj. Bahoku Barigye said four Somali civilians were killed in the mortar attack, while categorically dismissing Abu Mansur's allegations.

"We are not unloading weapons at the port, but we received vehicles and food donated by the world," the AMISOM spokesman stated.

He condemned Abu Mansur's armed group for killing "innocent Somalis as usual." At least seven other people were wounded in the attack.

President Sheikh Sharif had told reporters after spending three days in Mogadishu that he met with leaders of the insurgency, including representatives from al Shabaab and the Islamic Party, a new Islamist coalition. READ: President claims to have spoken with anti-govt groups

Somalia's former president, Col. Abdullahi Yusuf, had advised the incoming leader to confront al Shabaab, which is listed as a terror organization by the U.S. government.