National Front leader Le Pen appeared to distance herself from US President Donald Trump on Friday morning following the US strike on a Syria air base, which was carried out in response to a suspected chemical attack.
She said on Twitter that she "strongly condemned" the "horrible" strike on the Syrian air base.
"Is it too much to ask that we wait for the results of an independent international investigation before carrying out a strike like this in Syria?" she told the France 2 channel on Friday morning.
Trump said that he was acting in America's "vital national security interest" in the hope of preventing further uses of chemical weapons.
Le Pen's response to the air strike takes a different tone to the one she took after Trump was elected in November, when she was quick to congratulate him and insist that his win would be good for France.
Her view conflicted with that of France's President Francois Hollande, who said that Syrian President Bashar al-Assad bore "sole responsibility" for the US strike.
"After the chemical weapons massacre of April 4 on Khan Sheikhun in northwestern Syria, a military installation of the Syrian regime was destroyed by a US air strike last night," he said in a joint statement with German Chancellor Angela Merkel.
"President Assad bears sole responsibility for this development."