Lawmakers and presidential candidates from both parties yesterday lauded the Reagan administration's decision to launch a military strike against an Iranian oil platform as a reasonable and restrained response to Tehran's missile attack on a U.S.-flagged tanker.

But critics of the U.S. policy of reflagging Kuwaiti vessels in the Persian Gulf warned that the nation may be drawn deeper into the regional conflict and said the incident demonstrated anew the need for the president to invoke the War Powers Resolution.

Senate Majority Leader Robert C. Byrd (D-W.Va.) characterized the administration's response as "minimal and appropriate," but said he is "concerned that we may be backing into war with Iran." Byrd once again urged President Reagan to comply with the terms of the 1973 war powers act, which 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 has said does not apply to the U.S. presence in the Persian Gulf, requires the president to report to Congress within 48 hours of the deployment of U.S. forces and requires those forces to be withdrawn within 60 days unless Congress declares war or extends the deadline.

House Speaker Jim Wright (D-Tex.) said Congress is generally "supportive of what was done" and congressional leaders believe it is important to show Iran that it cannot expect to attack U.S.-flagged vessels "without expecting measured retaliation."

Although Wright said this is not the time "to get into a quarrel" with the administration over the war powers law, the U.S. strike came as the Senate prepared to resume its long, divisive debate over U.S. policy in the gulf.

The Senate is scheduled to take a key vote today on a compromise measure, pushed by Byrd and Sen. John W. Warner (R-Va.), that questions the reflagging operation while sidestepping the war powers question. Attempts to trigger the law since July have been blocked by a Republican-led minority.

The Byrd-Warner amendment, while expressing support for a continued U.S. presence in the gulf, expresses reservations about the reflagging operation. It would require Reagan to provide within 60 days a report to Congress on the escort operation. Within 30 days of that report, Congress would have to act on an unspecified resolution that could either continue the policy in the gulf, end it or modify it.

Some Democrats predicted the U.S. retaliation could build support for the Byrd-Warner amendment. But others suggested that near-unanimous support for the administration in this instance would not clarify the Democratic-controlled Congress' halting and confused efforts to come to grips with a policy many lawmakers find troubling.

"The issue is not so much our presence in the gulf, but the open-endedness" of the policy, said House Majority Leader Thomas S. Foley (D-Wash.)

Underscoring divisions among Democrats was a statement by House Armed Services Committee Chairman Les Aspin (D-Wis.) calling the U.S. response to the Iran attack "probably too mild."

Sen. John Glenn (D-Ohio) called the U.S. attack "a measured response that showed we are not just going to roll over and play dead" in the gulf. But Glenn warned that the United States is traversing a "slippery slope" and said "the president would be well advised to report to us under the war powers act so he can have congressional support, which I think he would get."

Republican leaders of the House and Senate, meanwhile, offered unqualified support for the retaliatory strike and said Reagan complied with the spirit of the war powers act.

House Minority Leader Robert H. Michel (R-Ill.), who was among congressional leaders briefed on the operation by Reagan Sunday night, called the attack "a measured, appropriate response." He said the administration's action, including the briefing and a promise to report on the incident with 48 hours, "is certainly within the spirit of the law if not the letter of the law."

Senate Republican leader Robert J. Dole (R-Kan.), who was campaigning for his party's presidential nomination in New Hampshire yesterday, issued a statement saying, "The ayatollah asked for this, and he got it."

"We've sent the message again," added Dole. "And if Khomeini ignores it, again, he'll get more of the same. It's that simple."

Other presidential contenders also backed Reagan's action.

Sen. Albert Gore Jr. (D-Tenn.) called the administration response "commendably disciplined, well-focused and well-executed," but said escalating tensions in the gulf make it "more important than ever for the president to secure the support of Congress, and the way to do that under the law is to invoke the war powers act."

Rep. Richard A. Gephardt (D-Mo.) called the U.S. attack "measured and proportional" but said it highlights the need "for the president to take real steps to lead the international community to bring meaningful pressure on Iran and Iraq to end the war."

Sen. Paul Simon (D-Ill.) called the attack a "measured response," but said, "This clear exchange of hostilities is added cause for invoking the war powers act."

Rep. Jack Kemp (R-N.Y.) praised the strike, called the war powers act "unconstitutional" and added, "We should be ready to take out Silkworm missile sites involved in such attacks."