The Soviet Union warned last night that more fighting in the Falkland Islands dispute between Britain and Argentina would pose "great danger," especially to "those who provoke" it.

Japan, meanwhile, urged Britain and Argentina to exercise restraint and prevent any escalation of the crisis, while British allies in the Commonwealth supported the attack on South Georgia.

The Soviet warning--included in the Kremlin's first substantive reaction here to the British retaking of South Georgia--did not specify the dangers the Soviet Union foresaw. It was in a commentary carried by the state-controlled television.

Criticizing mediation efforts by Secretary of State Alexander M. Haig Jr., the commentary said Britain and the United States were conspiring to increase NATO influence in the region.

"In our times, political problems are not solved with naval units and the neocolonialists will have to convince themselves of this," it said.

The Foreign Ministry insists that the Soviet Union is neutral in the dispute, favoring a peaceful settlement. However, Soviet news media consistently have argued that the dispute was caused by Britain's refusal to give up its colonial possessions, as urged by the United Nations.

Japanese Prime Minister Zenko Suzuki called the use of force regrettable at a time when Secretary of State Alexander M. Haig Jr. was making mediation efforts.

The warmest response came from New Zealand Prime Minister Robert Muldoon, who sent a message to British Prime Minister Margaret Thatcher calling the assault on South Georgia "a splendid feat of British arms."