Seventy-four senators introduced a resolution yesterday to block the Reagan administration from selling advanced weapons worth up to $1.9 billion to Jordan. But, despite warnings from Republican congressional leaders that the sale faces overwhelming opposition, President Reagan told them the sale is "essential to create the conditions for a lasting Middle East peace."

Sources familiar with the White House meeting said that Secretary of State George P. Shultz urged the Republican members to block an immediate vote on the resolution because he was hopeful that there might be positive developments in the Mideast peace process during the next few days.

Shultz's reported remarks fueled speculation that the administration might be planning some kind of dramatic initiative, such as an attempt by Reagan to bring about a meeting between Israeli Prime Minister Shimon Peres and a representative of Jordan's King Hussein, perhaps when the president is at the United Nations on Thursday.

However, State Department sources denied that such moves are under consideration. The sources said Shultz's remarks were prompted by the recent appeals for peace that Peres and Hussein made here and at the United Nations.

In a speech Monday to the U.N. General Assembly, Peres urged an immediate end to the state of war between Israel and Jordan and the beginning of peace talks. The State Department yesterday called his speech "a statesmanlike, thoughtful, forward-looking exposition" and a "reaffirmation of the urgency of moving forward in the peace process."

However, the resolution introduced yesterday under the leadership of Sens. Edward M. Kennedy (D-Mass.) and John Heinz (R-Pa.) would bar the sale of American-made jet fighters, missiles and other sophisticated weaponry to Jordan until Hussein begins direct peace talks with Israel. A similar resolution is expected to be introduced in the House later this week.

Sponsors of the resolution are anxious to bring it to a vote in the next few days before the administration can mount a strong lobbying effort against it. Senate Foreign Relations Committee Chairman Richard G. Lugar (R-Ind.), hoping to prevent an embarrassing defeat for Reagan and Hussein, was scheduled to meet with opponents today to seek possible ways of softening the ban on the arms deal.

Aides to Lugar said he probably would propose an alternative resolution to approve the sale, expressing support for Hussein's peace efforts but making an arms sale contingent on the start of talks with Israel. However, the aides, noting that the White House is reluctant to back any kind of compromise, said that if the idea does not win support, Lugar will step aside and let the Senate vote on the Kennedy-Heinz resolution.

White House spokesman Larry Speakes quoted Reagan as telling the Republican leaders, including Senate Majority Leader Robert J. Dole (R-Kan.) and House Minority Leader Robert H. Michel (R-Ill.), "The opportunity for peace must be exploited before it slips from our grasp . . . . The sale of defensive weapons is essential to this process."