Crowds of Somalis joined a demonstration on Monday against the jihadist group Al-Shabaab at the site of a deadly beachfront attack in the capital Mogadishu last week.

A suicide bomber and gunmen attacked the popular Lido Beach on Friday evening, killing 37 people and wounding scores more, in one of the deadliest strikes in the East African country in months.

"We came here to Lido Beach to show we can't be intimidated," said one of the protesters, Abdisalam Ahmed Abdullahi.

"Mogadishu people are not afraid of Kharijite enemy," he said, using a government term for the Al-Qaeda-linked Islamist militants who have carried out numerous attacks in the predominantly Muslim country for years.

Survivors of Friday's assault described how following an explosion, gunmen stormed onto the beach intending to "kill everyone they could," with graphic video shared online showing bloodied bodies on the sand.

Al-Shabaab has been waging a bloody insurgency against Somalia's fragile federal government for more than 17 years and has previously targeted the Lido beach area, which is popular with business people and government members as well as ordinary Somalis.

"Somali people in general, and those in Mogadishu particularly, need to unite in fighting against the enemy," said Livestock Minister Hassan Hussein, one of several government officials who joined the rally.

He described Al-Shabaab militants as "bedbugs."

Amina Ibrahim Halane said she joined the rally to show sympathy for the victims of Friday's attack, saying they were simply "innocent men... enjoying their city." (AFP)