MOSCOW, JULY 30 -- The legislature of Soviet Armenia today rejected a decree by Soviet President Mikhail Gorbachev last week that armed nationalist groups in the republic and elsewhere in the country must turn in their weapons and disband within 15 days or be disarmed by Soviet security forces.

The local lawmakers declared that Gorbachev's July 25 proclamation "contradicts the Armenian people's natural right to self-defense" as outlined in Armenia's Constitution, as well as the United Nations Charter, according to Ovanes Muradian, a spokesman for the leading Armenian nationalist movement.

The decree was Gorbachev's latest attempt to stem more than two years of conflict between warring ethnic groups in the Soviet Transcaucasus region and the country's Central Asian republics. The disturbances have left hundreds of people dead, caused millions of dollars in property damage and created tens of thousands of refugees, chiefly among the populations of the bitterly hostile Soviet republics of Armenia and Azerbaijan.

Soviet Interior Minister Vadim Bakatin said last week that military force would be used if the decree were disobeyed, but he acknowledged that problems could arise in implementing it without the full cooperation of local authorities.

Muradian, speaking by phone from Yerevan, the Armenian capital, said the Armenian declaration asserted that the republic could police itself without "outside interference" and that "Soviet army and Interior {Ministry} troops have no right to exercise any punitive actions on Armenian territory without permission" of its legislature.

Meanwhile, violence continued in the republic, as armed militants attacked guards at a factory on Sunday and stole a number of vehicles, Soviet televison reported. It said the campaign for residents to turn in weapons has had little effect in the republic and virtually none at all in Nagorno-Karabakh, a mostly Armenian-populated enclave controlled by neighboring Azerbaijan that has been the focus of the bitter dispute between the two peoples.

Bakatin said that besides Armenia, illegally armed groups operate in Moldavia, Georgia, Azerbaijan, Latvia, Lithuania, Estonia and the Central Asian region, where clashes between ethnic Uzbeks and Kirghiz have resulted in more than 200 deaths in recent months.

Bakatin estimated that 10,000 to 20,000 Armenians were involved in illegally armed groups but said others had put the figure as high as 100,000. He said internal security troops would be sent to republics requesting them and that army units could go in if a state of emergency were declared.