President Reagan charged today that House rejection of aid to the Nicaraguan rebels directly sparked the Sandinista incursion into Honduras and demonstrated that negotiations with Managua are futile.

In a political speech here delivered in advance of the Senate vote approving his request for $100 million for the rebels, Reagan lashed out at critics of his Nicaragua proposal, saying, "This Sandinista offensive is a slap in the face to everyone who voted against aid to the freedom fighters thinking it to be a vote for reconciliation."

Recalling that one opponent of aid to the rebels had said the House vote was a "sign of peace and friendship" to the Sandinistas, Reagan said, "The Nicaraguan communists took the House vote as a sign all right; they invaded the territory of Honduras with about 1,500 heavily armed troops and then they lied about it."

"This military drive demonstrates the nature of the Nicaraguan regime," he added. "The communists in Managua are not seeking dialogue and pluralism. They want total power in their hands and they have no respect for the borders of their neighbors."

Reagan's confrontational rhetoric came amid questions about U.S. assertions that the Sandinista force in Honduras numbered 1,500. Some U.S. intelligence sources have estimated it at less than half that size.

Questioned about the troop estimates on his arrival here, Reagan said, "The White House is giving you the truth as I think all of us know it." He added that "we knew there were two battalions" and the 1,500 estimate was based on "rough numbers" or estimates of each one. "Maybe those battalions were under strength or over strength -- we don't know . . . . "

Appearing at a fund-raiser for the Republican Senate candidate, Rep. W. Henson Moore (La.), Reagan said the counterrevolutionaries or contras "have bogged down the communist drive in Central America." He described the House rejection of his proposal for $70 million in military aid and $30 million in economic aid to the rebels as "reality turned on its head."

"At the same time our opponents claim to support negotiations, they move to eliminate any incentive for the communists to negotiate," he said. "They're not going to come to the table because they had a change of heart. They're going to come because the heat is on, and they get tired of the heat that the contras can impose upon them."

The president, who had remained silent in recent days on events in Central America and Libya, said today that during the 1970s the U.S. government was "paralyzed by uncertainty" and "permitted our defenses to erode and ignored a growing totalitarian threat."

But the "failures" of those years, he said, show that "crossing our fingers and hoping for the best is not the way to ensure a more peaceful world."

Saying that "serious negotiations flow not from proving sincerity but from resolve and leverage," Reagan said that since 1981 "we have struggled on Capitol Hill to prevent our negotiators from being stripped of their leverage prior to getting to the negotiating table. Time and time again we won, with only a tiny margin, votes essential to our security."

He criticized those who he said "loudly" proclaimed an interest in arms control while opposing "systems that persuade the Soviets to negotiate."

Reagan's remarks came at a $5,000-per-person fund-raiser for Moore, who is battling Democratic Rep. John B. Breaux to succeed Sen. Russell B. Long (D-La.).

Under this state's primary system, if either candidate wins more than 50 percent of the vote, he takes the seat. Thus, the outcome could be an early indicator in this fall's contest over the Senate, now controlled by the GOP. In early polls, Moore is leading Breaux, who is seeking to blame Moore for the state's troubled economy.

Reagan acknowledged that "economic troubles . . . persist" in the state, but credited Moore with working out a House-Senate agreement on offshore oil revenue that will give Louisiana $605 million this year. Breaux has attacked the deal as insufficient.

After his address, Reagan began a 10-day vacation at his California ranch.