President Reagan, amid intense administration infighting, has decided to delay at least until next week a decision on whether to abandon the limits of the unratified SALT II nuclear arms treaty, White House officials said yesterday.

The officials said a letter from Reagan is being sent to Capitol Hill saying he is unable to report by Saturday on whether to continue the "no undercut" policy regarding the SALT II limits that was in effect during his first four years in office. Such a report was due by June 1 under the terms of the 1985 Defense Authorization Act.

A White House official said Reagan wants time to meet with the National Security Council on the issue Monday and to consult with U.S. allies before reporting to Congress on the knotty issue. The new target date for the report to Congress is Friday, June 7, although officials conceded that any definite presidential decision early next week could leak out quickly.

Secretary of State George P. Shultz is scheduled to meet NATO foreign ministers in Lisbon next Wednesday and Thursday. An official said the SALT II policy is likely to come up then, although perhaps by that time Shultz may inform allies of Reagan's decision rather than ask their views.

Some NATO allies have been led to expect consultations on the issue by the United States before next week's NATO meeting, diplomatic sources said. Most of them prefer that SALT II limits be retained lest their abandonment touch off an uncontrolled arms race that will raise political as well as military tensions.

"The feuding and fighting in the administration on this issue is intolerable," said a congressional source familiar with the maneuvering in the executive branch. This source said word reaching Capitol Hill is that Shultz, National Security Affairs Adviser Robert C. McFarlane, Joint Chiefs of Staff Chairman Gen. John W. Vessey Jr. and arms adviser Paul H. Nitze are against abandoning the SALT II limits, while Secretary of Defense Caspar W. Weinberger and some of his aides are for jettisoning the "no undercut" policy.

The Senate may debate the issue Tuesday when arms control amendments are to be in order to the 1986 Defense Authorization Bill. An aide said conservative senators, including Sens. Jesse Helms (R-N.C.), Steve Symms (R-Idaho) and Malcolm Wallop (R-Wyo.), will mount a filibuster about Soviet arms control violations if Senate liberals seek to arrange a vote backing continued compliance with SALT II before Reagan submits his report.

Arms adviser Edward L. Rowny, in a breakfast meeting with reporters, said "reams of paper" and "lots of meetings" within the administration have been devoted to the SALT II compliance question. As of yesterday morning, Rowny said, the administration is "very much in the throes" of discussion in an attempt to narrow the options for Reagan.

Weighing in publicly against abandoning SALT II limits was Rep. Les Aspin (D-Wis.), chairman of the House Armed Services Committee, who said yesterday that such an action "would run counter to our proclaimed goals and strategy" in the Geneva arms talks. In a speech to the Georgetown Center for Strategic and International Studies, Aspin said, "The message we send if we let SALT lapse is that we intend to mount a buildup of offensive arms. There would be no other reason to let the agreements lapse."

Abandoning SALT II limits might make Reagan's Strategic Defense Initiative plan, popularly known as "Star Wars," "utterly impractical," said Aspin, because the space-based defense would have to counter "a new order of threat" if the Soviet Union can freely expand its nuclear striking power with no restraints imposed by treaty limits.