Attorney General Benjamin R. Civiletti yesterday issued unprecedented immigration regulations to carry out President Carter's order to deport Iranian students who are in this country illegally.

The estimated 50,000 Iranian students will have to prove, within a month, that they are enrolled as full-time students and have committed no crimes of violence or they will face deportation proceedings, the order said.

Civiletti said he waived the normal notice requirements for government regulations as "impracticable and contrary to the public interest" because he was acting "in response to the international crisis created by unlawful detention of American citizens in the American Embassy in Tehran."

Administration officials have acknowledged that Present Carter ordered the action, at least in part, to placate American citizens who were outraged when Iranian students demonstrated recently in support of the government that is holding 60 to 65 American hostage in Iran.

David W. Crosiand, acting commissioner of the Immigrtion and Naturalization Service, told reporters yesterday that the new regulations are legal, through they are believed to be the first ever to single out a group from one country.

Crosland was clearly uncomfortable in aswering questions at the Justice Department briefing. He said he could not estimate how many Iranian students had violated to answer other questions about the numbers of Iranians in this country.

Other administration officials involved in the new program on Iranian students acknowledged that INS should have a better idea on the status of all foreign visitors, but does not because record-keeping is so outdated.

Crosland said he expected the colleges and the students involved to comply with the new orders. Students who do not cooperate will be considered in violation on their visas, and (INS investigators will go out looking for them, he said.INS has about 900 investigators to cover the country, with fewer than 20 in Washington and 14 in Los Angeles, both foreign student population centers. Crosland said INS personnel will be shifted around the counrry as needed.

Two professional groups representing U.S. educational exchange programs issued a statement yesterday saying, "It is essential that all foreign students in the United States do not become the scapegoat for U.S. indignation and frustration."

Ruth Jenkins, executive vice president of the National Association for Foreign Student Affairs, said he felt the INS survey would find the most Iranian students here are legaly enrolled in their schools.

"I see this as a necessary, if unfortunate, step that is acceptable if in the end these law-abiding students are exonerated and are left along," Jenkins said.

The Civiletti order says Iranian students must show proof of enrollment, course load, payment of fees and local address in the interview with INS officials.

Those not here legally can choose to leave the United States voluntarily, Crosland said yesterday. If they choose to fight deportation proceedings, the process could take several months, he said.

Students may file claims for political asylum if they fear they will be in danger in returning to Iran. Crosland added.

Some administration officials involved in the process have expressed concern privately that the new action could heighten, rather than calm, public reaction to the Iranian students.

"It's a very frightening situation," said one. "Despite all our talk about the Statue of Liberty, there seems to be a very thin veneer about people's reaction to foreigners." The same members of Congress who were demanding protection of Iranian students after the shah's fall from power are now demanding their deportation this official said.

Robert Rosenzweig, vice president for public affairs at Stanford University in Palo Alto, Calf., said last night that attorneys for the school will check the new INS regulations carefully before cooperating with the program for its more than 100 Iranian students.

The government shouldn't be able to make a new law to fill a particular political need," he said.