President Reagan has firmly reassured NATO allies that he does not intend to withdraw U.S. forces from Europe and has "no quarrel" with their current levels of defense spending.

This is the first time Reagan as president has promised explicitly to maintain troops in Europe, and he makes it at a time when many in Congress are calling for U.S. withdrawal to show dissatisfaction with European defense commitments.

He made it in an interview with four European newspaper and magazine reporters in Washington last week. A transcript of the interview was made available here today to reporters following the president.

The interview appears to be part of an effort to reassure Europeans on U.S. nuclear, economic and European defense policies before he travels to Europe next week, and to portray Reagan as anxious to reduce nuclear arms, strengthen the NATO alliance and understanding of European economic problems.

Reagan, here at his California ranch for a working vacation until Sunday, is to leave Washington Wednesday for a nine-day trip to France, Italy, Great Britain and West Germany. During the trip he is to participate in an economic summit at Versailles and a NATO meeting in Bonn.

In Washington today, White House communications director David R. Gergen told a breakfast meeting of reporters that Reagan views his upcoming European trip as a chance to score some public relations gains on foreign soil.

In pursuit of what Gergen described as "public diplomacy," Reagan is to make at least three major televised speeches during the trip: one at the Vatican, one before the British parliament and one before the bundestag in West Germany.

He also will give a half-hour interview to broadcast journalists from France, Italy, Germany and Great Britain that is expected to be aired Tuesday, on the eve of his departure.

"We view the trip as an opportunity for the president to reach the European public in a way he hasn't been able to before," Gergen said. "Many Europeans don't known him well and misunderstand what his policies are all about."

Administration officials said today that they expect anti-nuclear demonstrations during the visit because "many Europeans do not understand him well and misunderstand what his policies are all about."

In his interview with the European journalists, Reagan said that he enjoys a "very friendly . . . open relationship" with European leaders, but he acknowledged that there had been strains and "ill feeling on both sides" in the alliance. He said the strains existed when he came into office.

Reagan told the reporters that, "We have no intention of withdrawing troops, we recognize our responsibility there. We recognize that those troops are not there, as some have said in congressional debate, because we are generously doing something for someone else. Our own security is involved. We are there because that NATO line is our first line of defense."

Given the economic problems facing Europe, Reagan said, "I think that their defense spending level has been consistent. And I have no quarrel with it at all."

Administration officials said the subject of improved defenses would be on the agenda of the NATO meeting, but not specific dollar or percentage figures for the individual members.

Reagan defended his massive defense buildup proposal as necessary to bring the Soviets to the bargaining table.

"In recent years when we were letting our defenses crumble and were virtually unilaterally disarming, there was no incentive for the Soviet Union to meet us in any kind of arms reduction talks," he said.

Reagan praised NATO allies for indicating a willingness to accept Pershing missiles and cruise missiles.

"I know that politically in Europe this was a great problem in a number of countries because of the peace movement. Some people can't quite see that unilateral disarmament is not the road to peace," he said.

"The very fact that countries of Western Europe have said they were willing to base these missiles and we were willing to provide them is why the Soviets agreed to go to Geneva to meet . . . . I don't think they would have ever come to negotiate had it not been for the imminence of that proposal . . . . I would hope that before all those missiles are in place on our side, we would have negotiated an agreement in which they'll be unnecessary."

Reagan, however, expressed continued doubts about the Europeans' decision to participate in a pipeline deal to get energy from the Soviets.

The president also announced nearly $70 million in humanitarian food and medical assistance in the 1982 and 1983 fiscal years for 2.9 million needy people in Poland. The aid is to be distributed by CARE, Project HOPE and the Catholic Relief Service Programs.