Thousands of supporters of an Islamist militia have demonstrated for a second day in the Somali capital against the proposed deployment of foreign troops.
The US is accused of backing the defeated warlords
The protesters held placards with slogans such as "open your eyes and ears America, Sharia law is the only solution" and "democracy go to hell".
The Islamists control Mogadishu and much of the southern Somalia.
They say the interim parliament's decision to invite peacekeepers means they will not talk to the government.
"We offered the transitional government dialogue but it has unilaterally decided to bring foreign troops," Sheikh Abdulkadir Omar, deputy chairman of the Union of Islamic Courts told Mogadishu's Tarbuunka square, according to Reuters news agency.
Some of the strongest objections are to the idea that Somali's regional rival Ethiopia could contribute troops to the force.
They also criticised the US, which is widely believed to have backed the warlords defeated in Mogadishu by the Islamists.
President Abdullahi Yusuf wants peacekeeping troops to guarantee his safety before he goes to Mogadishu, where he does not have a strong support base.
His government, named after two years of peace talks in neighbouring Kenya, is based in Baidoa because the capital is too dangerous.
Meanwhile, the UN's World Food Programme (WFP) has warned of rising malnutrition rates in southern Somalia, caused by drought and the recent fighting.
WFP says 20% of children under five were so hungry they needed supplementary or therapeutic feeding.
An estimated 58,000 children need targeted feeding but current programmes reach fewer than 10% of these children, WFP says.
The insecurity has made it increasingly difficult for aid agencies to work in southern Somalia.
On Thursday, the first meeting in New York of a new international Contact Group on Somalia gave its backing to President Yusuf's government.
It also called for urgent aid to Somalia and said it intended to address international concerns over terrorism.
The UK, US, Norway, Sweden, Italy, Tanzania and representatives from the European Union took part in the talks at Norway's UN mission in New York.
The Islamist victory in Mogadishu is seen as a major setback for US policy in the region.
The US has neither confirmed nor denied reports it backed the warlords but says it will stop Somalia becoming a safe haven for terrorists.
Somalia has not had an effective national government for 15 years, during which time it has been fought over by a host of different armed factions.