World leaders have pledged to boost support for measures to fight piracy, terrorism and political instability in Somalia.
A conference in London on Thursday attended by 55 countries agreed a seven-point plan promising more humanitarian aid, support for African Union peacekeepers and better international co-ordination.
US Secretary of State Hillary Clinton said the world must keep the al-Shabab group "on the run".
A two-decade war has wrecked Somalia, leaving it without a proper government.
The current transitional government has direct control only in the capital, Mogadishu. It is propped up by 12,000 African Union peacekeepers.
Al-Shabab, which recently joined al-Qaeda, controls large swathes of territory.
Mrs Clinton ruled out talks with al-Shabab, saying that its decision to join forces with al-Qaeda showed "it is not on the side of peace, stability or the Somali people".
British Prime Minister David Cameron said setting up an inclusive government was vital to the country's future, and that it must work alongside military action by the African Union.
The BBC reports representatives from many Somali factions attended the London conference, but al-Shabab was not invited.
The group denounced the London conference as another attempt to colonise Somalia.
On Wednesday, Ethiopian and Somali troops took control of the strategic stronghold of Baidoa, in the south-west of the country, from al-Shabab.