Meeting Lebanese President Michel Suleiman after his arrival, Ahmadinejad said: "Lebanon changed the hostility equation in the region and tilted the balance in favor of its people. We are two peoples that love each other," Israel's Ynet News reported.
Suleiman thanked Iran for its support "in the face of Israeli aggression and the threats being uttered by it" and for "rebuilding Lebanon following the July  war."
The Lebanese president added, "States have a right to make use of nuclear capabilities for peaceful purpose, and Iran has this right too, via quiet dialogue and without any threats or violence against it."
American officials made their disapproval of Ahmadinejad's visit known last week, The New York Times reported.
Iran, which has long provided arms and training to Hezbollah, has also offered to equip the Lebanese army, which has gotten American support and training.
Ahmadinejad was to appear later Wednesday at a Hezbollah rally and to visit the movement's stronghold in southern Lebanon Thursday.