Soviet leader Mikhail Gorbachev, continuing his appeals to European opinion during a visit here, today said there were "broad possibilities" for disarmament in Europe, but the Soviet Union would not allow the United States to use arms negotiations as a "smoke screen" for a military buildup.

During a visit to a factory, Gorbachev said the danger of war in Europe had increased recently and that steps toward disarmament, confidence-building and respect for national borders were necessary for stability on the continent.

The Soviet leader repeated a long-standing Kremlin proposal for the joint dissolution of NATO and the Warsaw Pact and reaffirmed his willingness to meet with President Reagan if there is an "appropriate international atmosphere."

At the same time, Gorbachev said that it was often suggested that the United States was using talks as a "smoke screen" to hide a drive to achieve military superiority. According to a report on East German television, Gorbachev affirmed that "no one can use a smoke screen against us, and that goes for the summit as well."

The new statement on arms negotiation was the third Gorbachev has made since his arrival here last Wednesday and reflected a strong effort to convince Western Europeans that the Soviet Union is seeking disarmament "from the Atlantic to the Urals" while the Reagan administration is blocking progress.

Gorbachev has repeatedly stressed here "a new initiative" by Moscow to reduce the levels of troops and tactical aircraft in Europe. The proposal, he said in a speech last Friday, was an answer to concerns that the elimination of nuclear missiles from Europe could increase the danger of a conventional war.

The high profile assumed by Gorbachev in what he called "the platform" of Berlin has strongly overshadowed the East German communist party congress that he is nominally here to attend.

With the Kremlin chief looking on, the congress of the ruling Socialist Unity Party of East Germany closed today with a reaffirmation of the 15-year rule of Erich Honecker and a pledge to continue his rigidly conservative policies.

The 73-year-old East German leader raised his arm and clenched his fist in a salute as delegates cheered his formal reelection as party secretary general. Honecker then announced the promotion of three men to the ruling Politburo in a move that analysts here said strengthened his position and that of his protege and likely successor, Egon Krenz.

The five-day congress concluded without any hint that it had been influenced by Gorbachev's drive for more openness, self-criticism and reform of economic management in the Soviet Union.

Instead, Honecker and other communist leaders focused almost exclusively on the successes of the East German economy and vowed to press ahead with efforts to develop closer ties with West Germany and other western countries.