Kenyatta declared three days of national mourning starting Wednesday.
Kenyatta said forensic experts would examine the corpses of the assailants to determine their identities, softening earlier assertions by Kenya's foreign minister that Americans and a Briton were involved in the siege.
"Intelligence reports had suggested that a British woman and two or three American citizens may have been involved in the attack," the president said.
"We cannot confirm the details at present but forensic experts are working to ascertain the nationalities of the terrorists."