PARIS, Jan. 16  At a time when most world powers have forged a united front against Iran because of its nuclear program, President Jacques Chirac arranged to send his foreign minister to Tehran to talk about a side issue, then abruptly canceled the visit earlier this month in embarrassing failure.

Mr. Chirac’s troubles stemmed from his deep desire to help resolve the crisis in Lebanon before his term runs out in May. To that end, he decided to seek the support of Iran, which, along with Syria, backs the radical Shiite organization Hezbollah, three senior French officials said in describing the effort.

So he planned to send Foreign Minister Philippe Douste-Blazy to Tehran, only to call off the trip two days before it was to have taken place, said the officials, who spoke on condition of anonymity because they are not authorized to speak publicly on diplomatic issues.

Both Mr. Douste-Blazy and senior Foreign Ministry officials concluded that such a trip was doomed to fail and that it would send the wrong signal just weeks after the United Nations Security Council unanimously approved sanctions intended to curb Iran’s nuclear program, they added.