Opposition candidate Morgan Tsvangirai claimed victory after the March 29 presidential vote, but pulled out from a runoff citing political repression and murders. Mugabe, who has ruled the country for 28 years, won the one-candidate vote.
"We do not accept the legitimacy of any government that does not reflect the will of the Zimbabwean people," the leaders of Japan, Britain, Canada, Germany, France, Italy, Russia and the United States said in a statement adopted at a summit in north Japan's Hokkaido island.
"We deplore the fact that the Zimbabwean authorities pressed ahead with the presidential election despite the absence of appropriate conditions for free and fair voting as a result of their systematic violence, obstruction and intimidation," the statement said.
World leaders had insisted Zimbabwe should have cancelled the runoff.
The group expressed concern over the situation in the country, plagued by poverty and unemployment, and called on the authorities to allow humanitarian aid in. They also pledged financial and other measures to punish those responsible for the violence.
The leaders said they wanted to work with the African Union and the United Nations to resolve the crisis, and recommended that a UN envoy be appointed to prepare a report on Zimbabwe.
