The US Secretary of State John Kerry is set to travel to France later this week following criticism that Washington was under-represented at the Paris rally, which took place to condemn recent terror attacks in the French capital.
The top American diplomat said the US authorities including President Barack Obama are "deeply engaged" with French officials in expressing solidarity ever since the attack took place.
During a press conference in India, where Kerry is on an official visit, he said: "As everybody knows, I have been here in India for a prior planned event. I would have personally very much wanted to have been there but couldn't do so because of the commitment that I had here and it is important to keep these kinds of commitments."
Leaders of nearly 50 countries including British Prime Minister David Cameron, German Chancellor Angela Merkel, and Israeli Prime Minister Benjamin Netanyahu participated in the unity rally in Paris. More than 3.5 million people took part in unity marches across France held on Sunday.
The US was represented by Washington's ambassador to France Jane Hartley at the Paris march.
Kerry will also hold talks with French officials discussing further measures to tackle terror-related attacks.
Assuring the relationship between the two countries "is deeply, deeply based in the shared values and particularly the commitment that we share to freedom of expression," he said the US had "offered, from the first moment, our intel, our law enforcement, and all of our efforts".