BUCHAREST, Romania (AP) _ Parliament gave Premier Petre Roman a rare defeat today by rejecting two nominees to the new Cabinet he named to meet criticisms over skyrocketing prices and slumping economic production.

About 30,000 workers and students rallied in the western city of Timisoara to demand an end to Roman's National Salvation Front government.

Leaders of the Front tried to downplay the defeat in Parliament. Vasile Vacaru, head of the party's parliamentary faction, told state radio the rejections proved ''the parliamentary majority is not a rubber stamp that votes as it is instructed.''

The Front, which took power in the December 1989 anti-Communist revolution and won elections in May 1990, enjoys a two-thirds majority in Parliament.

But its public support slumped after food prices doubled last month, and experts are predicting millions of workers could be unemployed by the end of summer because of falling production in the economy.

The two nominees narrowly rejected by the Chamber of Deputies were Dinu Patriciu of the Liberal Party-Youth Wing, who was to become public works minister, and Radu Berceanu of the National Salvation Front, nominated as youth and sports minister.

The agreement by Patriciu, a leader in the major opposition group, to serve in the government had been seen as a coup for Roman. But deputies accused Patriciu of ''political adventurism.''

''He is considered an ambiguous figure, sometimes left-wing, sometimes right-wing ... who desires power,'' said Ioan Babos, a deputy who belongs to the Front.

Sources said Berceanu apparently was defeated because of internal Front politics.

The other nine Cabinet nominees, including two opposition leaders, were approved.

In making the nominations, Roman said Monday that he would ''proceed without delay to small- and large-scale privatization'' and other economic reforms.

The opposition press dismissed the Cabinet reshuffle. The newspaper Romania Libera said the new ministers were ''a new hat'' for the same government.

In Timisoara, protesters gathered in the city's Opera Square, site of the first rally that sparked the 1989 revolution, shouting ''Down with Roman'' and ''Down with communism.''

Vasile Popovici, a leader of the Civic Alliance opposition, called Roman ''the greatest tragedy for the country at this time.'' The Civic Alliance has accused Roman of incompetence in pursuing economic reform.