Beat Hess told French daily Le Figaro that the group was going through “a difficult phase” that was “a problem for the company's reputation”.
Lafarge is accused of paying the Islamic State group and other militants through a middleman in order to allow the company's factory in Jalabiya, northern Syria, to continue to operate.
It is also suspected of using fake consulting contracts to buy fuel from the Islamic State group, which took control of most of Syria's strategic oil reserves in June 2013.
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The Lafarge headquarters in Paris. Photo: AFP
“Unacceptable errors were made which the company regrets and condemns,” Hess said, adding that Lafarge “probably pulled out of Syria too late”.
Frederic Jolibois, who took over as manager of the Syria factory in 2014, has been charged with financing terrorism and violating an EU embargo on Syrian oil.
Bruno Pescheux, Jolibois' predecessor as factory chief between 2008 and 2014, and Lafarge security boss Jean-Claude Veillard were also charged with financing terrorism as well as “endangering others' lives”.
Hess, who became chairman of the company in May 2016, said that he had “full confidence” in the French legal system, and that “if we can help, we will do so”.