The US has issued a worldwide travel alert to its citizens, citing terrorist threats from Isis, al-Qaeda, Boko Haram and "other terrorist groups".
The alert from the US State Department urges US citizens to exercise caution in public places and during holidays and public events.
French President Francois Hollande will meet Barack Obama at the White House on Tuesday to discuss the fight against so-called Islamic State.
Americans will be informed of any credible terror threat on home soil, the US president has said.
In a speech following a security briefing, Barack Obama advised Americans to go about their business as usual ahead of the Thanksgiving holidays which start tomorrow.
He told reporters at the White House: "We know of no specific and credible intelligence indicating a plot on the homeland.
"But in the event of a specific credible threat, the public will be informed."
France and the US have agreed to step up airstrikes in Syria and Iraq to target IS in the wake of the Paris attacks.
Britain will do "all in our power" to support France in the fight against IS following the Paris terror attacks, David Cameron said.
The United Nations Security Council agreeS to intensify efforts to 'eradicate' Islamic State in the wake of the Paris terror attacks.