The report Monday said certain Democratic and Republican individuals recently conveyed messages of support to Israeli Prime Minister Binyamin Netanyahu and other government officials.
No American officials were named and there was no indication that the U.S. would participate directly in a military offensive against Iran, the report said.
Maariv said it was told by sources that if Israel decided to conduct a military strike on Iran's nuclear sites prior to the American presidential elections in November, President Barack Obama would order the U.S. military to support Israel.
The U.S. Army would provide a "defense umbrella" to counter possible missile attacks by Iran and its allies, including Hezbollah in Lebanon, the newspaper said.
Individuals who sent messages to Israel include some U.S. administration officials and advisers to Republican presidential candidate Mitt Romney, the report said.
Netanyahu is scheduled to meet Obama at the United Nations General Assembly next month.