"Soon they will accuse us of also building an atomic bomb."
The US, UK, China, Russia, France and Germany are putting pressure on Iran to hold face-to-face talks on its nuclear programme.
'Helping the oppressed'
The leader of the Andean nation met Mahmoud Ahmadinejad, the Iranian president, and Manouchehr Mottaki, the foreign minister.
The two countries are allies and Ahmadinejad said during the visit: "Helping the oppressed and revolutionary nations and expanding anti-imperialist fronts are the main missions of Iran and Venezuela."
Chavez will meet with other Iranian officials, including Ayatollah Ali Khamenei, the supreme leader.
It is the first visit by Chavez since Ahmadinejad was re-elected in a disputed poll in June.
The visit is part of a six-nation tour by Chavez and other high-ranking Venezuelan delegates. The group has already visited Libya, Algeria, Syria and will travel to Belarus and Russia after Tehran.
Chavez signed nine agreements with Bashar al-Assad, the Syrian president, as part of his attempts to strengthen an alliance against the US and Israel.
He said that Israel should return the Golan Heights to Syria and outlined common threats before flying on to Tehran.