Declaring there is still no real political change in the country, ElBaradei, 69, said in a statement, "My conscience does not allow me to run for the presidency or any other official position unless there is real democracy."
Elbaradei, who had played a significant role in the January revolution, said a fair election would not be possible under the military's grip.
The former IAEA chief said he had taken his decision in protest at the way Egypt's military rulers governed "as though no revolution had taken place".
He said yesterday that his decision does not mean a complete withdrawal from the political scene but that he will continue serving society "outside any positions of power, freed from all the chains".
The Nobel Peace laureate praised the revolutionary youths who led massive popular uprisings that toppled Mubarak last year but said "the former regime did not fall". ElBaradei's comments reflect growing disenchantment with the ruling Supreme Council of the Armed Forces (SCAF) which has been running Egypt since Mubarak was ousted in February last year following an 18-day popular revolt.
The Egyptian presidential election is scheduled to take place in June 2012.
The SCAF has repeatedly pledged to cede full powers to civilian rule when a president is elected by the end of June, but there is widespread belief that the military wants to maintain a political role in the country's future. ElBaradei had wanted a new constitution to be drawn up from scratch before any elections took place.
However, the SCAF opted to go ahead with parliamentary elections first.