Police raided a Nairobi estate on Sunday and arrested scores of people following Friday's violence in the capital that was blamed on an extremist group operating out of Somalia.
The overnight swoop in Eastleigh, where many Somalis live, saw 328 people suspected to be sympathisers of the Somali militia rebel group al Shabaab arrested.
A combined force of police and the General Service Unit carried out the operation, which began at 9 p.m.
Most of the arrests were at the Shariff Centre, 2nd Avenue on 7th street in the sprawling estate.
They were found in possession of identity cards that police believed to be fake.
Last week's demonstration to demand the release of radical Jamaican Muslim cleric Sheikh Abdullah al-Faisal turned violent as rowdy youths engaged police in running battles for six hours.
One person was killed in the chaos and several police officers injured.
The government blamed the violence on "foreign youths with extremist ideas," and assured Muslims that their rights will be protected.
Mr al-Faisal arrived in Kenya on December, 24 last year after travelling through Nigeria, Angola, Mozambique, Swaziland and Malawi and Tanzania.
He had been deported to The Gambia last week on the orders of Immigration minister Otieno Kajwang, but was returned on Sunday morning after Nigeria refused to give him passage.