The Reagan administration yesterday reiterated its position that Libya was behind attacks at the Rome and Vienna airports Dec. 27, despite Israeli statements that the terrorists were trained in Syria and operated from there.

"We have found no evidence of direct Syrian government complicity in the Rome and Vienna attacks," which killed 20 persons, State Department spokesman Bernard Kalb said. "Evidence exists for Libyan support for the individuals involved."

He noted, however, that Palestinian terrorist leader Abu Nidal has offices in Syria and Syrian-held Lebanon "and appears to have drawn on these resources in the airport attacks." Kalb said, "We believe that Syria should rid itself of Abu Nidal."

Israeli Defense Minister Yitzhak Rabin said Thursday in Jerusalem that "Libya deserves whatever has been said about it, but in this case I believe the terrorists' springboard came from Syria."

He did not give evidence, but added, "We have all the reason to believe that these terrorists . . . came from Damascus, which served as the training place for this mission and the source from where they got their instructions."

Disagreement on the terrorists' origins appears in part to reflect the differing Israeli and U.S. perceptions of Abu Nidal's importance. Some Israeli officials are known to be concerned that current U.S. stress on his terrorist leadership may divert attention from Syrian President Hafez Assad as a source of tension in the area.

In addition, a terrorist who survived the Vienna bombing is known to have said he was trained in the Bekaa Valley in Syrian-held Lebanon, which could point to Syria as originator of the attacks.

But U.S. analysts have said that Abu Nidal's training camps are located throughout the Middle East, including the Bekaa Valley, and that the attacks fit the recent pattern of indiscriminate violence that the analysts regard as the signature of Libyan leader Muammar Qaddafi.