Tonazzi made her international debut on 20 April 2002 in a 4–1 victory over the Czech Republic. Due to her amazing form domestically, she was selected to play at the 2003 FIFA Women's World Cup, where France suffered elimination in the group stage. She was among the leading goalscorers for her nation during the qualifying process for UEFA Women's Euro 2005 netting five. However, she would not be selected to play in the tournament. She made her return to major international play after she was selected by Bruno Bini to play in UEFA Women's Euro 2009. However, she did not make an appearance.