Washington, U.S., (Reuters): French Foreign Minister Jean-Marc Ayrault said on Thursday that France is still seeking a United Nations Security Council resolution on Syria, adding that diplomatic negotiations were a priority over possible military action.

A suspected chemical attack by government forces in Syria's rebel-held Idlib province earlier this week, which killed at least 70 people, has sparked widespread criticism, including from U.S. President Donald Trump.

Ayrault told the media that France was pursuing a U.N. resolution condemning the attack and trying to convince allies to back it, in spite of pushback from Russia.

The foreign minister said, "France is still seeking to talk with its partners on the Security Council, especially the permanent members, and Russia in particular."

He was more cautious on whether or not France, one of the main backers of the Syrian opposition to President Bashar al-Assad, would contemplate a military intervention if the United States decided to take action and ruled out stepping in for now.

Earlier on Wednesday Trump said that Assad's government had gone "beyond a red line" with the poison attack on civilians, but did not detail how he might respond.

U.S. ambassador to the United Nations Nikki Haley warned that countries "could be compelled to act."

Ayrault said, asked whether France would join any possible U.S military operation, "The first stage is to get a resolution vote and above all to re-start peace negotiations in Geneva. It is not to go in ourselves, under the pretext that the U.S. President may have a rush of blood to the head, and get onto a war footing."

Ayrault added that the U.S. response on Syria was still unclear, and that he was getting mixed messages from his counterpart, U.S. Secretary of State Rex Tillerson, and Defense Secretary Jim Mattis.

"They're not saying the same thing," he said.

France has repeatedly said that Assad cannot be part of a credible solution on Syria as part of peace talks, and along with Britain renewed its call this week for the Syrian president to leave office.

"His crimes cannot remain unpunished. The day will come when international justice will have its say on Bashar al-Assad," Ayrault said.