POLAND--President Bush, in a day of high symbolism and support for Poland's strides toward democracy, yesterday offered a modest economic aid package intended to help "redeem the promise of a free Polish republic."

A key element of the package is the $100 million U.S. fund--provided Congress approves, to support the Polish private sector as the Soviet bloc country moves away from its Marxist economy.

But the dimensions of the U.S. offer could fall short of Lech Walesa's aspirations. The leader of the Solidarity trade union movement is expected to ask Bush today when they meet in Gdansk to back a $10 billion program of international help for Poland.

Even so, a clearly exhilarated Bush assured the Polish parliament, where Solidarity holds 260 of the 560 seats, that "the Western democracies will stand with the Polish people, and other peoples of this region."

But Bush stressed that the aid would come with a string attached--that Poland would have to adopt austerity measures.

Bush told the parliament that Poland must choose either a free market economy or socialism. "Your responsibility for your country's future is immense," he said.

Prime Minister Mieczyslaw F. Rakowski told Bush the speech "contained many thoughts permeated with realism." But Foreign Minister Tadeusz Olechowski said his nation was not looking for "a rain of gold."

Secretary of State James A. Baker III told a news conference the primary objective of the U.S. aid package is to lower Polish inflation from its current 100 percent rate and to ease government subsidies for heavy industry.

Included in his offer of financial assistance,Bush:

.Pledged to ask Congress for a $100 million"enterprise fund" to support Polish entrepreneurs.Moreover, he said he will ask other industrializeddemocracies to undertake similar initiatives atthis weekend's western economic summit meeting inParis.

.Said he would ask Congress to approve $15million to fight air and water polution in Krakow.

.Promised to open a U.S. educational andcultural center in Warsaw and asked Poland to dothe same in the United States.

.Told the parliament he would ask his sixsummit partners to quickly support rescheduling ofup to $5 billion of Poland's $39 billioninternational debt.

.Said he would encourage the World Bank toproceed with $325 million in loans to help Polishagriculture and industry "reach the productionlevels that they are clearly capable of."

Although interrupted by applause five times andgiven a standing ovation at the end of his speech,Bush encountered little more than a correctresponse from the parliament and a tepid receptionon the streets of Warsaw.

The approximately 4000 people who watchedBush's 12-car motor-cade drive through the streetsof Warsaw waved small paper American flagslistlessly. Occasionally there were shouts of"Long life. Long life."

The president would up his busy day as guest ata state dinner hosted by the Communist Partyleader, Gen. Wojciech Jaruzelski. Striking muchthe same tone as in his speech to parliament, Bushsaid in a toast that Poland was entering a new eraand was "beginning, once again, to command its owndestiny."

Bush also squeezed in a short pitching sessionwith the Polish Little Leaguers. The well-attendedsession was designed to support the development ofAmerica's national pastime in this Europeancountry