India denies coming under US pressure to back a resolution paving the way for Iran to be referred to the UN Security Council over its nuclear plans.
Iran insists it wants civilian nuclear power, not weapons
An Indian foreign ministry statement said the International Atomic Energy Agency (IAEA) resolution was consistent with Delhi's stated position on Iran.
The statement said India's vote was in no way linked to a recent landmark India-US nuclear accord.
Officials hoped a $7bn gas pipeline deal with Iran would be unaffected.
"We see no reason why there should be any apprehension in this regard," the statement said.
"India has played a constructive role in the IAEA and helped safeguard Iran's legitimate interests."
The IAEA resolution was passed 22-1 with 12 abstentions on Saturday. Venezuela was the only country to vote against it. Russia and China abstained.
Many observers were surprised that India, which has close ties with Iran, decided to vote in favour.
Key left-wing allies of the government accused it of buckling under US pressure, which the Indian foreign ministry denied.
"There is no question of India having ranged itself on one side or the other," the foreign ministry said. "Nothing could be further from the truth."
A spokesman said India, on the contrary, had played a helpful and supportive role in safeguarding Iran's right to peaceful use of nuclear energy.
The vote in Vienna came hours after Indian Prime Minister Manmohan Singh urged Iran's President Mahmoud Ahmadinejad to be prepared to make concessions in order to avoid confrontation.
Iran denies seeking nuclear arms, saying it wants nuclear technology purely for peaceful production of energy. It has called the resolution illegal.