A higher education bill fast-tracked through parliament on April 5 has been widely seen as directly targeting the Central European University (CEU), founded by US billionaire George Soros in 1991.
The law has triggered the largest series of protests seen in Budapest since Orban came to power in 2010.
Another law that would force nongovernmental organisations (NGOs) to register as "foreign-funded organisations" was submitted earlier this month, and has also prompted international condemnation.
Calling international politics "a theatre of conflict" Orban said in an interview that "migration lies at the centre of that theatre of conflict".
"The Soros university, the transparency of international lobby organisations (...) are all secondary theatres of conflict," he told pro-government daily Magyar Idok.
The New York-registered Central European University (CEU), founded by Soros in 1991 and long considered by the government as a hostile bastion of liberalism, says it could be forced out of Hungary as a result of the new rules.
Institutions from outside the European Union will not be able to award Hungarian diplomas without an agreement between national governments.
They will also be required to have a campus and faculties in their home country -- conditions not met by the CEU.
The legislation has drawn international condemnation including from the US State Department, whose spokesman last week urged Budapest to "suspend" its implementation.
Another demonstration expected to draw over 10,000 people is scheduled to take place in the Hungarian capital later on Saturday.
The Hungarian-born philanthropist Soros, 86, has often been accused by Orban during the past two years of seeking to undermine Europe by backing open borders and pro-refugee policies.
"This affair is about George Soros hiding before the public eye the fact that he supports illegal immigration via his Hungarian organisations," Orban told Magyar Idok.
"He pays several lobby organisations disguised as civil groups in order to assert his own interests. He maintains an actual network, with its own advocates, its own media, hundreds of people, and its own university," Orban said.
The Hungarian premier, 53, has built border fences to keep out migrants, and placed asylum-seekers in border "transit zone" camps, part of a hardline anti-immigration policy since 2015 that has won him plaudits at home but criticism abroad.
"Those who call themselves liberal or leftwing and who are supported with money, power, and networks of international forces - with George Soros at the head - say that taking measures against migration is wrong, impractical, or immoral," said Orban.
"In contrast we want to protect the essence of Europe, we don't want parallel societies, we don't want to replace our population, and we don't want to swap our Christian civilisation for another kind".
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