The Senate, spurred by the U.S. shelling of an Iranian oil platform and growing displeasure with the military escort of Kuwaiti tankers, voted 67 to 28 yesterday to break a Republican filibuster that had blocked efforts to influence administration policy in the Persian Gulf.

The vote to invoke cloture paved the way for action on an amendment that would express reservations about placing Kuwaiti tankers under the protection of the U.S. flag and call for a vote in 90 days that could lead to modification or termination of U.S. military operations in the gulf.

Although a substantial number of senators say they fear that the administration's reflagging policy could draw the country into a war with Iran, a Republican-dominated minority filibustered for a month to block a tougher measure that would trigger provisions of the War Powers Resolution of 1973. That resolution, often called the war powers act, limits presidential authority to deploy U.S. military personnel in areas "where imminent involvement in hostilities is clearly indicated by the circumstances."

The law, which Reagan contends does not apply to U.S. presence in the Persian Gulf, requires the president to report to Congress within 48 hours after deployment of U.S. forces and requires that those forces be withdrawn within 60 days unless Congress declares war or extends the deadline.

To break the stalemate, Senate Majority Leader Robert C. Byrd (D-W.Va.) and Sen. John W. Warner (R-Va.), ranking Republican on the Armed Services Committee, moved yesterday to invoke cloture on their milder substitute amendment expressing reservations over the reflagging policy while endorsing continued U.S. presence in the Persian Gulf region. The 67-to-28 vote, seven votes more than the necessary 60, had the effect of shelving the amendment to immediately trigger the War Powers Resolution.

"We need to lay to rest whatever uncertainty exists of support in Congress for our president," Warner said. "The Byrd-Warner amendment leaves the war powers act intact . . . . The law needs revision, but now is not the time to revise it."

Byrd said, "Nobody suggests we pull our forces out of the Persian Gulf. What people have concern about is the reflagging and convoying of Kuwaiti ships."

Following the cloture vote, Byrd scheduled a final vote on his amendment at noon today.

Sen. Lowell P. Weicker Jr. (R-Conn.), cosponsor of the resolution to trigger provisions of the war powers act, said he would back the Byrd-Warner amendment, although, he said, "it still seeks to avoid the law of the land -- the war powers act."

Sen. Lloyd Bentsen (D-Tex.), who opposed earlier efforts to force the administration's hand, said the U.S. retaliation against Iran for last week's Silkworm missile attack on a U.S.-flagged tanker in Kuwaiti waters "tipped the scales" in favor of ending the filibuster.

"We have a conflict, and it's too important for one man to make that decision," Bentsen said. "I'm one of those who strongly supports the president's objectives in keeping the sea lanes open. But I'm opposed to reflagging because it puts Kuwait in the position to jerk our foreign policy around."

Senate Minority Leader Robert J. Dole (R-Kan.) opposed the cloture motion, arguing that the Senate was straying into "a very dangerous and sensitive" area of foreign policy without fully understanding implications of the Byrd-Warner amendment.

Under that amendment, the president would be required to submit a detailed report within 60 days to provide a review of the range of U.S. commitments and military involvements in the Persian Gulf. Then, 30 days after the report is filed, the Senate would vote on an as-yet undefined resolution that, according to Byrd, could do anything from declare war in the gulf to cut off funds for any further military involvement.

"We don't have the foggiest notion of what will be in that resolution," Dole said. "If someone could tell me what we're going to vote on in January or February, it might be okay."

Warner said the amendment has the virtue of allowing the Senate to take whatever action it cares to -- or no action at all -- without triggering the 60-day clock contained in the War Powers Resolution. "You do not have that jackhammer pressure {on the president} to bring out the troops," he said.

On the crucial vote, 17 Republicans joined 50 Democrats to invoke cloture. Sen. David L. Boren (D-Okla.) was the only Democrat to vote against cloture. In this area, Sens. Paul S. Sarbanes (D-Md.), Barbara A. Mikulski (D-Md.) and Sen. Paul S. Trible (R-Va.) backed cloture.