She said her thoughts and prayers, including those of her family, were with those families affected and the first responders called to duty that day.
Her statement said: “As we mark the 20th anniversary of the terrible attacks on September 11 2001, my thoughts and prayers — and those of my family and the entire nation — remain with the victims, survivors and families affected, as well as the first responders and rescue workers called to duty.”
In her message, she recalled her own visit to the World Trade Center more than a decade ago.
She said: “My visit to the site of the World Trade Center in 2010 is held fast in my memory.
“It reminds me that as we honour those from many nations, faiths and backgrounds who lost their lives, we also pay tribute to the resilience and determination of the communities who joined together to rebuild.”
It comes after Boris Johnson said terrorism had failed to make people live in “permanent fear” in a defiant message to mark the day.
He added: “But while the terrorists imposed their burden of grief and suffering, and while the threat persists today, we can now say with the perspective of 20 years that they failed to shake our belief in freedom and democracy; they failed to drive our nations apart, or cause us to abandon our values, or to live in permanent fear.
“The fact that we are coming together today – in sorrow but also in faith and resolve – demonstrates the failure of terrorism and the strength of the bonds between us.
“Recent events in Afghanistan only strengthen our determination to remember those who were taken from us, cherish the survivors and those who still grieve and hold fast to our belief in liberty and democracy, which will always prevail over every foe.”