Mo Ibrahim spoke Monday at the launch of his foundation's 2009 Index of African Governance, which tracks development on the continent.
He said African leaders must "stand firm" against those who seize power and then try to legitimize their rule by holding elections.
Human rights groups say 157 people were killed when troops opened fire at a rally in Guinea last week. Capt. Moussa "Dadis" Camara seized control of the West African country in December. Elections are to be held January.
Ibrahim also referred to Madagascar, where a military-backed politician toppled an elected president in March.