That's exactly what I meant. A lot of people in the US don't follow politics in Europe, but those who do are unlikely to think Berlusconi was a president when he was actually a prime minister.
Prime ministers in Italy are also called Presidente del Consiglio dei Ministri, therefore technically yes. He was holding the executive power, and although Italy is a parliamentary republic, most of the laws are driven by the Government.
Did people really think that Berlusconi was the president of Italy?