New Soviet leader Mikhail Gorbachev met for nearly four hours with House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass) and three other U.S. congressmen today and said the United States had shown "absolutely incomprehensible haste" in dismissing the Soviet Union's moratorium on medium-range missiles.

By promptly rejecting as "propaganda" the Soviet move of last Sunday, Washington raised doubts about the sincerity of its approach to ongoing arms talks in Geneva, the Soviet news agency Tass quoted Gorbachev as saying.

"A kind of ice age is being observed in relations between the U.S.S.R. and the United States," said Gorbachev, adding parenthetically that this, at least, had been the case "until the most recent time."

He said the Soviet leadership had shown its desire to return the relationship "to a normal channel" and challenged Washington to display similar political will.

At a press conference after the unexpectedly lengthy meeting at the Kremlin, O'Neill said the discussion ended in "an amiable spirit" and was relatively free of confrontation.

O'Neill said he delivered a letter to Gorbachev from President Reagan, the second message from the White House hand-carried to the Soviet leader since he was chosen general secretary of the Communist Party March 11.

In the second letter, Reagan reportedly reiterated his invitation to meet Gorbachev. Last Sunday, Gorbachev said he had given a "positive" response to the invitation, but without agreeing on a time or place.

Tass announced tonight that Soviet Foreign Minister Andrei Gromyko and U.S. Secretary of State George P. Shultz would meet in Vienna May 14. A summit is considered one likely issue to be discussed.

Both O'Neill and House Minority Leader Robert H. Michel (R-Ill.), also present at the Kremlin meeting today, said Gorbachev indicated he is still awaiting a formal reply to a letter he sent to Washington last month.

"It was quite obvious that he is most interested in receiving . . . a more thorough response to his letter," Michel said. According to Michel, the message handed to Gorbachev today was not intended to be a response to his letter.

White House officials said O'Neill was not carrying a response from Reagan to Gorbachev's latest letter. Rather, O'Neill was carrying a "reaffirmation" of Reagan's desire for a meeting with Gorbachev, Washington Post staff writer David Hoffman reported from Santa Barbara, Calif., where the president is vacationing.

Reagan intends to send the Soviet leader a formal reply to his letter, but it has not yet been prepared, one official said.

"Knowing my president, I think the two could eventually get together and have a spirited conversation and dialogue," Michel said. He also paraphrased Gorbachev as saying that a meeting between Reagan and the Soviet leader "would be a good omen."

O'Neill said he was "tremendously impressed by Gorbachev's ability, talents, frankness and openness" during their discussion. "He would make an excellent trial attorney, an outstanding attorney in New York if he lived there," said O'Neill. "He's a master of words, a master of the art of politics and diplomacy . . . he's hard, he's tough, he's strong."

Both the Tass account and the congressmen said the Soviet moratorium on medium-range weapons, set to last until November, was fully discussed at today's meeting.

According to Tass, Gorbachev said Washington's claim that the freeze would leave the Soviet Union with a superiority in nuclear weapons was "an utter distortion of the facts."

"Mikhail Gorbachev cited concrete facts and figures to show the guests that, in real fact, there is a parity, a rough parity between the Soviet Union and the NATO countries in all of these weapons," Tass said.

The text of Gorbachev's statement Sunday said the moratorium applied to medium-range missiles and "other reply measures in Europe" taken in reponse to the deployment of NATO Pershing II and ground-launched cruise missiles in Western Europe. According to Soviet officials and diplomats here, the freeze on medium-range weapons also applies to those targeted on Asia.

According to NATO figures, the Soviets now have 414 triple-warhead SS20s, of which two-thirds are aimed at Western Europe. NATO has deployed 143 single-warhead medium-range missiles since the fall of 1983 in West Germany, Britain, Italy and Belgium.

But the Soviets have insisted that the independent nuclear arsenals deployed by France and Britain, a total of 162 missiles, should also be considered because they also represent a threat to the Soviet Union.

The congressmen confirmed today that Gorbachev disputed NATO calculations on the current nuclear balance in Europe, but would not elaborate.

"He went on at some length to say he did not agree with the figures given by U.S. Defense Secretary Caspar Weinberger . This was not unexpected," said Michel. "That is why we get together to talk privately."

The delegation is here as part of a parliamentary exchange program. The group arrived on Sunday and is scheduled to return to the United States next Monday.

While the administration has described Gorbachev's freeze proposal as a propaganda ploy, O'Neill said: "I like to believe that the general secretary was speaking his mind, heart and feelings for world peace. I don't want to look on it as propaganda."

The visit of the high-level U.S. congressional delegation coincided with a trip here by Dutch Foreign Minister Hans van den Broek. Western diplomats have widely interpreted the timing of the Soviet initiative as aimed primarily at the Netherlands, where a decision on the deployment of 48 cruise missiles is to be adopted on Nov. 1.

The Dutch stated last June that if the level of Soviet SS20s -- then numbering 378 -- increased by November, they would go ahead with the decision to deploy.

At a press conference today, van den Broek said he had asked Gromyko for Soviet deployment figures and received none. Nor, he said, did Gromyko challenge the NATO figure.

Van den Broek said that, in the absence of any other information, the Dutch decision to deploy would be based on the NATO figures, which indicate that the Soviet build-up has continued since June.

He said he was "disappointed" by the Soviet response to the Dutch appeal and noted that the moratorium imposed Sunday also implied that deployments had continued since June.

During their three days of meetings with a number of Soviet officials, O'Neill and the other 12 members of the delegation have repeatedly raised human rights questions, the fatal shooting of a U.S. Army major by a Soviet soldier in East Germany, as well as arms control and regional issues.