Virtually assured of hosting the seventh summit of nonaligned nations here early next year, India views itself as not only assuming leadership of the Nonaligned Movement for the next three years but also enhancing its role as a major actor in world affairs.

While the summit, which is expected to be held here in February or March, almost certainly will boost India's world role, it is also likely to dredge up a myriad of U.S.-Indian differences on issues that Prime Minister Indira Gandhi and President Reagan glossed over in their meeting in Washington last month.

The summit meeting is also likely to focus attention on a few issues on which India has strayed from the consensus of the 94-member Nonaligned Movement, including Indian abstentions on U.N. resolutions condemning the invasion of Afghanistan by Soviet troops.

There has been no formal announcement of the site of the seventh nonaligned summit, originally scheduled to be held in Baghdad next month, and Indian officials vigorously denied having courted the movement to hold the meetings here.

Gandhi, who was visiting Mozambique, said Thursday, "If everyone wants us to host the meeting, we'll have it. But it's not in our hands," Agence France-Presse reported. She added: "We would like a decision as soon as possible, one way or the other."

On Aug. 9, Iraqi President Saddam Hussein, bedeviled by the war with Iran and faced with intractable opposition by some nonaligned leaders who feared the spectacle of Iranian bombing attacks during the summit, offered in a personal message to Gandhi to step aside as host in favor of India, provided that the movement's foreign ministers convened in Baghdad next month to ratify Iraq as host of the eighth summit in 1985.

Cuba, host of the last nonaligned summit and current leader of the movement, insisted that the foreign ministers' meeting be held in Havana, causing a stalemate that has delayed formal announcement of New Delhi as host capital.

Indian officials said, however, that since Cuba, Iraq, Iran, Yugoslavia and most other nonaligned members publicly have favored New Delhi for the seventh summit, they assume it will be held in the Indian capital.

"The movement is going through its usual stresses and strains, but we are not going to make any preparations that look like preemptive moves. Everyone has a right to say his piece," a senior official of the Foreign Ministry said.

Throughout the stalemate, India has been careful not to antagonize either Iraq or Iran, each of which sells India about 26 million barrels of oil a year. India also has been an active member of the Nonaligned Movement's Persian Gulf war conciliation group.

For several years, India, which with Yugoslavia and Egypt was one of the principal founders of the Nonaligned Movement 21 years ago, has attempted to increase its stature in the organization.

Its influence had slipped some as a result of the Sino-Indian war in 1962 and two wars on the subcontinent in 1965 and 1971, but in the last two years it found itself directly at odds with a majority of the movement when it abstained on three U.N. resolutions calling for Soviet troop withdrawal from Afghanistan, and cast similar abstentions on resolutions calling for the withdrawal of all foreign forces from Cambodia.

Indian officials dismissed those abstentions today as irrelevant to India's leadership role among the nonaligned, and denied that India's stature in the movement had lesssened because of its close ties to the Soviet Union.

"It is true the vast majority voted to condemn the Soviet Union, but it has never been that every member of the movement must hold the same views," one official Indian source said. "There always will be a process of debate, and we see our function as encouraging that debate while maintaining the basic unity of the movement."

The implications for U.S.-Indian relations of India's ascendancy to the leadership of the nonaligned seem even broader, and U.S. diplomats here are following the summit developments closely.

As host country, India will be responsible for preparing draft resolutions on issues of vital concern to the Reagan administration, including the Middle East, South Africa, Central America, Afghanistan, South Africa and the Indian Ocean, a topic dominated by Mauritius' demand for the return of Diego Garcia and other islands of the Chagos archipelago that are leased to the United States by Britain for a strategic base.

The United States and India have deeply ingrained differences over all of those issues. Although the disputes arose during Gandhi's recent talks with Reagan in Washington, they were largely swept aside in the atmosphere of thawing relations between the two countries.

Of particular importance to the United States will be the Middle East, since it is likely that reverberations from Israel's invasion of Lebanon and an expected renewed U.S. effort to breathe life into the Camp David peace process will coincide with the start of the nonaligned summit. Egypt, which was expelled from the Arab League after signing its peace treaty with Israel, has remained a member of the Nonaligned Movement and is likely to find itself in the spotlight during the summit, according to Western diplomatic sources.

Indian officials stressed, however, that the nonaligned agenda and the Gandhi-Reagan meeting should be viewed as two unrelated events.

"What was clear from that visit was that while there was a change of tone, there was an insistence by both sides that there was no change on substantive issues of difference. There was a change of tone, but no change of policy," one Indian official said.

India's immediate problem, officials said, is to begin preparing the logistics for the summit once the foreign ministers announce New Delhi as the site. Indian officials said they expect to accelerate and expand on plans already under way to host a Commonwealth conference, adapting the plans to accommodate the 90 heads of state expected for the nonaligned conference.