Moslem guerrillas vowed today to continue their war against the new Afghan government installed Thursday in a Moscow-engineered coup, as Soviet troops consolidated their hold on the capital, Kabul.

Guerrilla leaders rejected conciliatory statements by the new Afghan government, branding the new premier, Babrek Karmel, a "puppet" of the Kremlin.

According to diplomatic sources, it took the thousands of Soviet troops recently airlifted into Afghanistan 3 1/2 hours Thursday night to seize control of Kabul from forces loyal to the deposed president, Hafizulla Amin. cAmin, a younger brother and a nephew were promptly executed after the takeover.

The official radio today announced a new 11-member Cabinet under Karmel, a hard-line communist considered more pro-Soviet than his predecessors. The radio also announced a curfew amid reports of continuing resistance by Amin followers.

Shortly aftger the coup Karmel was declared secretary general of the People's Democratic Party, president of the Revolutionary Council, prime minister and commander in chief of the armed forces.

In announcing the new Cabinet, which includes key officers purged from the previous government, Radio Kabul said the Revolutionary Council had asked the Soviet Union to continue financial aid and extend military assistance under a friendship treaty between the two countries signed a year ago.

The treaty was invoked in an apparent effort to justify the massive influx of Soviet troops into Afghanistan and their new combat role in support of the government.

The Afghan capital was reported largely quiet today as Soviet troops patrolled the streets and manned armored personnel carriers and other vehicles at key intersections. Kabul's airport was closed to commercial traffic and most communications with the outside world were cut.

There were unconfirmed reports that sporadic shooting continued today as supporters of the toppled president resisted the coup.

According to reports reaching here, Soviet forces engaged in heavy fighting Thursday night with loyalist Army troops to seize control of the presidential palace and the official radio station before installing Karmel in power.

Witnesses quoted in the reports said two Afghan Army tanks were destroyed by the Soviets, who were seen taking away regular Afghan troops as prisoners after a short but fierce battle that began at about 9 p.m. and ended around midnight. Soviet Mig 21s wheeled overhead but there were no reports that they took part in the battle.

There was no immediate estimate of casualties.

Despite announcements by the official radio that Amin had been tried by a revolutionary tribunal and executed for "crimes against the nation" -- a reference to his prosecution of the war against Moslem insurgents -- Afghan guerrilla spokesmen in neighboring Iran and Pakistan said they would not be fooled by what they called a substitution of "Moscow puppets."

Amin took over in a palace coup in the fall in which then-president Mohammed Taraki was overthrown and killed. Taraki had emerged as Afghanistan's head of state after a Moscow-backed coup toppled nonaliged president Mohammed Daoud in April 1978. After each coup a progresively more pro-Kremlin leader has taken power.

With tension still running high after the latest coup, Karmel has not yet appeared in public although he has made a number of radio broadcasts.

The fighting in Kabul provided the first concrete evidence that Soviet troops were taking combat roles in Afghanistan, whose pro-Moscow governments have been under siege for more than a year by rebellious Moslem tribes. The rebels control most of the countryside, leaving only the major cities in government hands.

Diplomts here speculated that the Soviets moved in with their massive show of force because Amin had failed to broaden his political base and stem the rebellion.

"The Soviets may have seen Army recruitment going down, desertions going up and the unwillingess of troops to engage the enemy," said a diplomat.

Although Amin was also pro-Soviet, he had defied the Kremlin in September when then-president Nur Mohammed Taraki returned from Moscow with orders to purge Amin, who was considered Taraki's hatchetman, and win more political support for the government.

Instead, Amin staged a countercoup against Taraki, who was reported fatally wounded in a shootout.

But, observers here said, Amin then became a marked man. He had defied the Soviets, alienated Taraki's supporters and failed to end the rebellion.

The key question now is the loyalty of Afghanistan's 50,000-to 80,000-man Army, which has been badly demoralized by a series of purges and the continuing civil war.

The fact that the Amin government was overthrown so quickly seemed to indicate that most Army units were going along with the Soviets, who had placed advisers down to the company level.

The Soviets also maintain a capability of intervening even more forcefully.

Besides, the 10,000 Soviet troops in Afghanistan, another 50,000 are massed on the borders ready to move if needed. In effect, said one observer, the Soviets could replace the entire Afghan Army with their own troops.

The Soviets moved their troops in openly over the past week in what a diplomat here called "a deliberate show of force" that indicates the Soviets are in Afghanistan to stay.

"It's chilling to me," said a Western diplomat, " that the Soviets have demonstrated their willingness to commit troops in a region like this that is so unstable. If they have done it here, they might do it elsewhere.

The Soviets cited a bilateral agreement between Moscow and Kabul as justification for its move into Afghanistan. Radio Kabul echoed the Soviet statement when it said the new Afghanistan government had requested "political, moral, economic and military assistance to restore normalcy and to repel an external threat."

The radio also accused Amin of being "an agent of U.S. imperialism."

The soviet statement bore a striking similarity to that issued in 1963 when Soviet and other Warsaw Pact troops marched into Czechoslovakia because they felt the government there had become too liberal.

The Afghan coup marked the first time Soviet troops have been used in that manner since 1968.

The Soviets obviously laid the groundwork well for this move. Besides, having effective control of the military through their advisers, the Soviets were able to reinstate a group of leaders who had been purged over the past 18 months by Taraki and Amin.

These leaders belong to the Parcham (Banner) wing of the Afghan People's Democratic Party, while Taraki and Amin belonged to the Khalq (Masses) wing.

Karmel, the new president and secretary general of the party, was deputy prime minister of Taraki's government right after the April 1978 coup, Soon afterward, though, he was sent into virtual exile as ambassador to Czechoslavakia, and he refused to return to Kabul after he was recalled to face an apparent purge.

Another key figure of the 1978 coup, Lt. Col. Mohammed Allam Watanjar, also emerged in the new government after having escaped a death threat from Amin last September.

Sultan Ali Keshimand was named prime minister and vice president of the Revolutionary Council.

The rebelling tribesmen who have been threatening the central government for more than a year took no part in the coup, according to information received here.

Although Karmel appears in control now, observers here said he needs the protection of the Soviet's military might.

Like the two presidents before him since the 1978 coup, his move to the top has left supporters of his political opponents unsettled and angry.Although he has promised to free political prisoners, most observers here believe he will refill the jails with his opponents.

"He will have to eliminate his opposition," said one observer.