Soviet leader Mikhail Gorbachev, meeting today with Libyan leader Muammar Qaddafi's deputy, pledged unchanging support for Libya but issued a veiled warning against terrorist acts that could serve as "pretexts" for "imperialist attacks."

Gorbachev's talks today with Maj. Abdul Salaam Jalloud focused on "conclusions which arise from the U.S. armed raid on Libya" in April, according to the Soviet news agency Tass.

Moscow is playing host this week to high-level delegations from Libya and Syria, its two foremost allies in the Arab world. As Jalloud met with other Soviet leaders, including Premier Nikolai Ryzhkov, Syrian Vice President Abdul Halim Khaddam arrived for talks with Soviet officials.

The United States said the April 15 attack on Libya was in retaliation for Qaddafi's support of terrorists, and in particular for Libya's alleged involvement in the bombing of a West German discotheque on April 5.

The Soviet Union has strongly attacked the United States for the bombing, which it has charged was an example of "state terrorism."

"The moral and political setback suffered by the United States does not rule out new ventures," Tass said, in a report on Gorbachev's talks with Jalloud.

"Therefore, there is the need for vigilance, steadfastness and a high level of defense capacity of countries which may become a target of an imperialist attack, and the need for adherence to principle and consistency in the condemnation of those pretexts which imperialists use and, first of all, terrorism in any of its forms," said the Tass summary of the conversation.

Jalloud arrived here yesterday on the first official visit by a Libyan since the U.S. bombing raids on Tripoli and Benghazi. He is expected to press Moscow for the replacement of damaged military equipment, diplomats here said.

Khaddam's visit was only announced yesterday, and western diplomats here speculated that the timing may not have been coincidental, although it was not clear what might link the two visits.

Jalloud was met at the airport by Soviet Defense Minister Sergei Sokolov. This was taken as a sign that military supplies were an issue.

The Libyan may again press for a friendship and cooperation treaty with the Soviet Union. But the Soviet Union is not thought likely to agree to a closer relationship with Qaddafi, who is regarded here as an unpredictable ally.

Diplomats said the subject of unity within the Palestine Liberation Organization may come up in talks with Khaddam. Gorbachev met with PLO leader Yasser Arafat twice in East Berlin last month during the course of the East German communist party congress.

The meetings were seen by some diplomats as an indication of closer rapport between the Soviets and Arafat's wing of the PLO. Soviet officials have lectured Syria publicly on the need for harmony within the organization -- in which Syria has backed an anti-Arafat splinter.

In meetings yesterday with British members of Parliament, Gorbachev warned that any attacks on Syria or PLO bases would have "incalculable consequences," according to an account by labor leader Denis Healey. Gorbachev apparently was responding to speculation on possible antiterrorist attacks.

After the U.S. bombing raids on Libya, the Soviets retaliated by cancelling a May meeting between Foreign Minister Eduard Shevardnadze and Secretary of State George P. Shultz. An attack on Syria would produce much harsher Soviet reaction, diplomats here agree.