BANGKOK, Thailand (AP) _ Cambodian resistance leader Prince Norodom Sihanouk and Indonesia's foreign minister said today that peace talks on Cambodia would go on, despite Vietnam's hints it won't participate.

''I am ready to go to Jakarta on the 25th of July with my partners of the coalition,'' Sihanouk said after meeting with Secretary of State George Shultz. ''We will be there.''

A State Department spokesman said Shultz gave Sihanouk a letter from President Reagan repeating U.S. positions that Sihanouk has a central role in a Cambodian settlement and that the Khmer Rouge should be shunned. It said the United States will continue to pressure Vietnam to withdraw its troops from Cambodia.

Reagan's letter invited Sihanouk to visit Washington this year.

Indonesia's Foreign Minister Ali Alatas, who is organizing the talks, said they were still on.

''There is no intention to recast the terms of the meeting,'' he told reporters when asked about Vietnam's charges that Indonesia and its allies were trying to turn the informal talks into negotiations between Vietnam and the Cambodian resistance.

Sihanouk and Alatas were in Bangkok for an annual meeting of foreign ministers of the Association of Southeast Asian Nations, or ASEAN, and counterparts from Japan and several Western nations. Shultz is attending the meeting as part of nine-country tour of Asia.

Vietnam's Foreign Ministry issued a statement Thursday saying the ASEAN ministers' joint communique issued this week prolonged the 9-year-old deadlock on the conflict and undermined the Indonesia talks. The communique voiced strong support for the Cambodian resistance.

The statement said ''such a hostile communique released by the ASEAN countries heralds their negative stance'' at the talks. With such a stance, the talks ''will not bring about expected results,'' it said.

The statement was carried by the official Vietnam News Agency, monitored today in Bangkok.

Sihanouk heads a coalition of resistance groups fighting the Vietnamese- backe d government in Phnom Penh. The coalition includes the Khmer Rouge, which killed hundreds of thousands of people during its 1975-78 rule.

Vietnam ousted the regime and set up a new government in 1979. It has promised to withdraw 50,000 soldiers from Cambodia this year and the other 50,000 by 1990.

Sihanouk said the Khmer Rouge wants to retake power in Cambodia. He said it was not possible to disarm the group because China, its main source of weapons, was not in favor of that.

He favors forming a national army comprising the three guerrilla groups and the government.

''If the Khmer Rouge were a member of the quadripartite organization, then I think they would not be able to exploit the situation,'' he said.

On Thursday, Shultz said the United States is ''unalterably opposed'' to the Khmer Rouge reclaiming power.

ASEAN members include Thailand, Malaysia, Indonesia, the Philippines, Singapore and Brunei.

The Vietnamese statement said the foreign ministers deliberately repeated a stance that has ''caused confrontation between Southeast Asian countries'' and ''resulted in the deadlock to the (Cambodia) issue over the past nine years.''

It said the group was trying to protect the Khmer Rouge, and ignored the fact that the pro-Hanoi government has control over the country.