"I strongly condemn today's terrorist attacks in Mogadishu," British foreign secretary William Hague said in a statement.
"The actions of terrorists only prolong the suffering of the Somali people.
"The UK and the international community... remain committed to helping the people of Somalia achieve peace, security and development," he added.
"Those responsible for terrorist acts should face justice."
A nine-man suicide commando blasted its way into Mogadishu's main court complex Sunday, some blowing up their explosives vests while others sprayed gunfire in a rampage that left 29 civilians dead, while a separate bomb attack killed five more.
The Al-Qaeda-linked Shebab militant group claimed responsibility for the courthouse attack.
Sunday was the worst day of violence the city has seen in months.