A reported attack on the convoy of Mahmoud Ahmadinejad, Iran's president, was actually a teenager throwing a firework, officials and a witness say.

Khabar Online, an Iranian website, had reported earlier on Wednesday that a homemade grenade exploded near Mahmoud Ahmadinejad's motorcade in western Iran. He was unhurt in the incident, the website said.

It said the incident occured as Ahmadinejad was on his way to address a gathering, and that one person had been arrested.

But a witness to the incident told Al Jazeera that a teenager threw a fire-cracker that landed near the convoy. The witness said that the youth was taken away, but did not believe that it was a genuine assassination attempt.  

Al Jazeera's Alireza Ronaghi, reporting from Iran, said: "Presidential sources say a firecracker went off near Ahmadinejad's convoy. They deny it was anything bigger than that and say Ahmadinejad and his entourage are OK.

"When I contacted the president's office in Tehran [the capital of Iran], officials vehemently denied any such incident," he said.