NEW YORK, June 28 (Reuters) - Al Gore insists he's campaigning for the environment these days, not for president.

The former U.S. vice president, whose documentary film "An Inconvenient Truth" about global warming won two Academy Awards this year, faces persistent speculation that he might make a run for the White House in the November 2008 election.

"I'm not planning to be a candidate again for office," Gore told Reuters on Thursday, repeating a now familiar denial at the launch of a "call to action" for Live Earth concerts around the world on July 7 to focus attention on climate change.

"I'm involved in a different kind of campaign to spread awareness of the climate crisis and the way to solve the climate crisis," he said.

"If this campaign is successful, it will put pressure on all of the candidates for every office in all parties to do the right thing on the climate."

Gore -- a Democrat who served under President Bill Clinton and narrowly lost the disputed 2000 election to the current Republican president, George W. Bush -- said it was too early to comment on the possible impact of a third-party presidential candidate in next year's election.

Many observers blame Green Party candidate Ralph Nader for siphoning votes from Gore and helping Bush win in 2000.

"There are 500 days between now and the U.S. presidential election, and it's way too premature to speculate on anything," Gore said.

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