Juppé was visiting the United Nations in a push for a resolution on Syria's bloodshed, said that a report by Arab League monitors was not definitive on the origin of the fire that killed 43-year-old journalist.
"We've asked the Syrian authorities for a transparent investigation and as of now we don't have the results of this investigation," Juppé told reporters.
In a speech earlier before the Security Council, Juppé said: "It was up to the Syrian authorities to give him all necessary protection. I understand that that wasn't the case."
The Arab monitoring mission said that Jacquier could have been killed by opposition fire "but the Arab League hasn't endorsed this theory and we're still waiting for the Syrian authorities to shed light on the incident," Juppé said.
Syria's ambassador to the United Nations, Bashar Jaafari, in a speech before the Security Council flatly blamed the opposition for Jacquier's death as he questioned why France was pressing against President Bashar al-Assad.
France has joined Arab states, Britain and the United States in seeking a UN resolution that would call on Assad to end violence and hand over power ahead of talks on a political settlement.
Jacquier was the first Western journalist to die covering Syria's uprising, which human rights groups say has killed more than 5,400 people over 10 months.
An AFP photographer said Jacquier was killed on January 11 when a shell exploded among some 15 journalists covering demonstrations in Homs. Eight Syrians were killed, said Syrian news agency SANA, and several other people were wounded.