The White House has snubbed the Christchurch Call to Action, but says it stands with the international community in condemning terrorist and violent extremist content online.
"While the United States is not currently in a position to join the endorsement, we continue to support the overall goals reflected in the call. We will continue to engage governments, industry, and civil society to counter terrorist content on the internet," the White House said in a statement.
The New Zealand Government has been lobbying the US to endorse the Christchurch Call to Action, due to be released at 4am (NZT), for several weeks, including having government officials visit the USA.
It is expected to be signed by at least 10 governments and several major tech companies, but the absence of the US is seen as denying a stronger mandate.
US President Donald Trump also did not accept an invitation to be in Paris for today's summit.
In a statement, the United States Government said it supported tech companies to enforce their existing community standards, and supported ways to redirect social media users away from dangerous online narratives that could lead to radicalisation.
"We continue to be proactive in our efforts to counter terrorist content online while also continuing to respect freedom of expression and freedom of the press.
"Further, we maintain that the best tool to defeat terrorist speech is productive speech, and thus we emphasise the importance of promoting credible, alternative narratives as the primary means by which we can defeat terrorist messaging.
"We welcome the continued momentum provided by support for the Christchurch Call as we work with international partners towards our mutual objectives for an open, interoperable, reliable, and secure internet."
The Call to Action will be voluntary framework whereby governments and tech companies pledge to work towards stopping violent content from being posted online, and preventing such content from spreading so rapidly.
Key parts will include preserving freedom of expression, abiding by international human rights law, and respecting a free, open and secure internet.
The pledge will lay a platform for further action, which the governments and tech companies will determine respectively and collaboratively.
There will also be an expectation for governments to adopt a legal framework in their respective countries to make tech companies more responsible for the online content they host.
The call will be the first agreement to include both heads of state and tech companies, and will seek to address concerns over whether tech companies are doing all they can to reduce online harm, and whether they've become such global juggernauts that they are essentially answerable to no one.