"The jury is out ... If I become prime minister I will judge him on deeds, not words," Truss said on Thursday during the campaign event in Norwich.
Her opponent in the prime minister race Rishi Sunak described Macron as a friend of the UK.
Truss and Sunak are the two final candidates in the premiership election race, which came after outgoing UK Prime Minister Boris Johnson announced his resignation on July 7.
The last round of voting in the Tories' leader race is taking place until early September. During the last round, all members of the party — around 200,000 people — will choose the winner from the two finalists. The voting will take place by mail. Johnson's successor will be announced on September 5.