Gunmen loyal to the Joint Islamic Courts (JIC), cut electricity, cleared cinema halls and warned residents against watching the football tournament in areas they control, forcing a violent protest late on Saturday in which two people were killed, residents said.
The JIC deputy chairman AbdulKadir Ali Omar said the Islamic tribunals would crackdown on halls that defy the order to show western films and video, including the World Cup.
"This is war against all people who show films that promote pornography, drug dealing and all forms of evil," Mr Omar said.
"We shall not even allow the showing of the World Cup because they corrupt the morals of our children whom we endeavour to teach the Islamic way of life."
Meanwhile heavily armed Islamic militia deployed north of the lawless Somali capital on Sunday, stirring fears they will shatter a week-long lull in fighting by attacking the last stronghold of the US-backed warlords' alliance.
Hundreds of Islamic fighters left Hiilweyne military camp, about 23 kilometres outside Mogadishu and headed north towards the warlord's remaining stronghold in Jowhar, about 90 kilometres away, military sources said.
A militia member told AFP that the deployment, which included dozens of pick-up trucks mounted with machine guns, was organised by Hassan Abdullah Hersi al-Turki, a member of the Somali militant group Al-Itihaad Al-Islamiya, accused by western intelligence agencies of being linked to Al-Qaeda.
Alarmed by the move, militiamen from the warlords' alliance bolstered their defences in Jowhar, residents said.
Gunmen enforce ban
Islamic courts officials said they were against some elements of World Cup, notably the advertisements for alcohol.
On Sunday, residents said Islamic gunmen were roaming in Sukahola and Huriwa neighbourhoods in northern Mogadishu to ensure that the ban was enforced.
"I had spent a lot of money on the equipment, which I intended to help me show the World Cup, but just an hour before the kick-off of the first game of the World Cup, two gunmen from the Islamists came to me and ordered me to close down my cinema," said Ali Mohamed Nuur, who owns a cinema hall.
"I thought that I was only suffering from this Islamic court order, but next morning I realized that all the cinema halls had been closed down," said Mr Nuur.
A strict interpretation of Islamic teachings often bans Western films and television as immoral.
"The Islamic courts have ordered the closure of three cinema halls," said Sukahola resident Abdulaziz Hanad. "They want to make sure that nobody in Mogadishu watches the World Cup."
"Since the Islamic courts took control of Mogadishu, we knew they would not allow us to watch football," said a dejected Dahir Abubakar Hassan, a resident of northern Mogadishu.
"I wanted to entertain myself from the trials and tribulations of the monotonous life in Mogadishu by watching the World Cup, but now I am not allowed," complained Halan Ahmed Mohamed, one of the protestors. "It is too silly to oppress people like this."
Last year, the courts started to forcefully close cinema halls, arguing that they were showing steamy Bollywood and Hollywood films.
Fears of Taliban-like regime
Last Monday, the Islamists defeated the warlords and seized control of most of Mogadishu, sparking fears of a Taliban-like takeover, with the forcible imposition of Sharia law, but the court's leader Sheikh Sharif Sheikh Ahmed said he would not impose the laws unless civilians called for them.
Somalia pulled out of international sporting events after the country
plunged into anarchy following the violent ouster of dictator Mohamed Siad Barre in 1991.
But residents in other pockets of Mogadishu still under control of the warlords gathered in makeshift cinema halls and watched the tournament that was being relayed from Germany through satellite dishes.
In the remaining warlords' stronghold of Jowhar, about 90 kilometres (55 miles) north of Mogadishu, residents gathered in public cinema halls to watch the 32-nation tournament, an AFP correspondent said.
"If only they can hold the peace for one month and allow us to watch football," Hassan Omar, a teenager in Jowhar said.