Sen. Henry M. Jackson D-Wash., normally a leading congressional hawk, yesterday criticized the Carter adminstration efforts to impose economic sanctions against Iran, urging a more conciliatory approach.

Jackson warned that such sanctions could backfire by fostering a regional breakup of the Persian-dominated nation and a possible communist takeover. He urged the U.S. government to "rethink our approach" to seeking the release of the American hostages in Tehran "by moving the other way and demonstrating our deep concern" for Iran's future.

"I seriously question the validity of sanctions as being an effective means of solving the hostage issue," Jackson, a senior member of the Armed Services Committee, said at a luncheon with reporters.

White House press secretary Jody Powell later rejected Jackson's criticism, saying his "view is an interesting, worthwhile consideration, but our judgement differes."

Powell said the uncertainties now confronting Iran stem largely from the "preoccupation" of Iranian officials with the hostage crisis and their "inability" to deal with other problems, rather than from any U.S. actions.

While objecting to U.S. sanctions against Iran, Jackson conceded that he had no specific plan for freeing the hostages. "I don't have the answer," he said.

"No one as yet has come up with a foolproof Entebbe operation," he added, referring to the celebrated 1978 Israli rescue of 103 hostages in Uganda. "You can't do it. You'd kill the hostages."

At the same time, he proposed that the United States embark on a far-reaching effort to secure the safety of Middle East oil supplies for Western nations. He said these oil reserves were endangered by the Soviet invasion of Afghanistan and unrest in Arab nations.

Jackson, who chairs the Energy Committee, called on Carter to announce a policy, backed by security agreements with other nations, to protect the Arab oil fields.

Under these agreements, Jackson suggested, "friendly forces" in the Arab world would be called on to step in military to block any threat to an oil-producing nation.

Egyptian officials have assured him, Jackson said, that "they are ready, willing -- with obvious help from the United States -- to play a role" in such an undertaking. By relying, at least initially, on Mideast military forces, Jackson said, the United States would avoid a direct confrontation with the Soviet Union over oil.

At the same time, Jackson called for a long-term U.S. military buildup, resumption of military draft registration and moves to strengthen the Cia. "The Western world cannot permit the oil fields to fall into unfriendly hands," he said.