The ministry of interior has said in a statement that he is unable to put his name forward for the presidency of the country’s South-West state as he still faces sanctions.
The announcement comes a day after Mr Robow declared his intention to run.
He is the highest ranking al-Shabab militant to defect from the group, despite being one of its founders.
Mr Robow had expressed his willingness, if he won, to forge a strong relationship with the federal government, which has been feuding with some state administrations.
In 2000 he trained with al-Qaeda in Afghanistan.
He left al-Shabab in 2012 because of what he called ideological differences. He then led his own group of militants who often fought against al-Shabab.
In June last year, following reports that Mr Robow was in talks with the Somali government, the US State Department removed him from its terror list and scrapped a $5m (£3.85m) reward for his capture.