Forgive me, I’m not positive whether you mean Reza Shah, the first monarch of the Pahlavi dynasty, or Mohammed (Reza) Shah, his son and successor. Either way, the answer, for the most part, is yes: both men ruled more or less autocratically during their reigns. Both men pushed programs meant to Westernize and modernize Iran, as well as reduce the power of traditional groups, in particular the ulema, who in particular tended to bristle against the kings’ reforms. The Majles tended to be largely, if not entirely, made up of delegates supporting the current Shah’s policies, and the prime ministers appointed by the Shahs were no different. Reza Shah was brought to power on the back of strong military support and opposition to the then-current ruling Qajari dynasty. He enjoyed the broad support of the Majles through much of his rule, though as time wore on he became increasingly protective of his hold on power; Hidayat (in Qudsizad) quotes the slogan “every country has its own ruling system and ours is a one man system.” Most of the Majles elected in his reign had little-to-no oppositional factions, a trait that would continue in a good portion of his son’s rule as well.

Mohammed Shah’s first decade was decidedly against this autocratic pattern; after his father was forced to abdicate in 1941 by the occupying Allied forces, the Majles asserted its independence, and the young Shah usually acceded to the deputies’ choice of prime minister (whoever had the support of the most parliamentary factions). Over this decade, the Shah began to slowly consolidate and rebuild the central power of the monarch. One aspect of this was in 1951 to institute the Senate, a legislative body that had been included in the 1906 constitution but had never been established; the constitution provided that half of this sixty-member body be appointed by the monarch.

The big event that heralded the Shah’s return to power was the downfall and overthrow of Prime Minister Mosaddegh in 1953 by international forces in alliance with parts of the Iranian military. This is a topic that has been discussed at length in other areas, but one of its outcomes was to finally curtail the independence of the Majles and prime minister, and to reinforce the position of the Shah. From 1953 onwards, the Shah centralized and enhanced his power at the expense of elected representatives; he worked to eliminate serious opposition, including vocal clerical opposition led by Ruhollah Khomeini who went into exile in 1964. “[F]rom 1964 to 1978 … Mohammed Reza Shah was more than ever the absolute ruler of the country.” (Bakitari 47)

Sources:

Bakitari, Bahman. “Chapter One: Dimensions in Prerevolutionary Politics.” Parliamentary Politics in Revolutionary Iran: The Institutionalization of Factional Politics. University Press of Florida, 1996. Google Books

Helen Chapin Metz, ed. Iran: A Country Study. Washington: GPO for the Library of Congress, 1987.

The Pahlavi Dynasty: An Entry from Encyclopaedia of the World of Islam. Edited by Gholamali Haddad Adel, Mohammad Jafar Elmi, Hassan Taromi-Rad. EWI Press, 2012. Google Books