Iran defender Milad Mohammadi scored an own goal in the 71th minute at the Stade 7 Novembre de Rades.
Soon after, Team Melli put the host under pressure to equalize the match but lacked a cutting edge.
The teams have met just once in the past. It was in August 2002 in a friendly match where they drew 2-2.
Iran, who had defeated Sierra Leone 4-0 last week in a warm-up match, has been drawn in Group B of the 2018 World Cup along with Spain, Morocco and Portugal.
Iran selected Tunisia for the friendly due to its game similarity with the Moroccan national squad.
Carlos Queiroz’s team will play Algeria in another friendly on March 27 in Austria.