The Prime Minister of Iran at the time was Mohammad Mosaddegh who had been elected in the Parliamentary elections of 1950. Mosaddegh had plans to kick Britain out of the oil business there, and nationalize it. The Anglo-Persian Oil Company had been in business since 1909. It later became the British Petroleum Company.
It was Britain that asked our CIA to help them overthrow Mosaddegah in 1953, and return Iran to complete Monarchy rule. Iran's past history, and the brutish interference of both of our countries is likely what brought on the coup of 1979. It was all about oil and money then, and still is.
WRONG!
The roots of the disastrous 1979 revolution go back far beyond Mosaddegh’s attempted coup (thats what is was) are found decades before. The 1906 constitutional revolt in 1906 leading to the Pahlavi Dynasty in 1925, and the Bolshevik Revolution in 1917 which spurred the Islamists and communists to move against Pahlavi.
Reza Shah Pahlavi admired Ataturk and wanted to modernize and secularize his nation too. Land reforms, removing mandatory veils and other moves toward female equality were too much for the mullahs. Giving women the right to vote in 1962 was probably the last straw.