The elite trained Danab forces have destroyed vehicle laden with explosives during an operation in the Lower Shabelle province.
"They were planning massive operations and suicide car bombings against the people of Somalia," Ahmed Abdullahi Nur, commander of the US-trained elite forces told the military radio.
Ahmed said over five militants had been killed during the operation which was conducted on Friday.
He said that the troops will intensify operations against al-Shabab fighters in those areas until they are wiped out.
Al-Shabaab, which is seeking to establish an Islamist state in Somalia, controls large areas in the south and centre of Somalia and repeatedly attacks security forces and civilians.