Reuters/James Lawler Duggan
The spokesperson would not elaborate on why Kerry, who was in Davos for the World Economic Forum this week, won't be attending the inauguration.
Kerry's announcement came after more than 50 Democratic lawmakers said they will be following Representative John Lewis' lead and boycotting the inauguration.
Lewis, a Georgia Democrat, told MSNBC last week that he did not consider Trump to be a "legitimate president" because he thought Russian hacking had helped get him elected in November. Lewis also skipped George W. Bush's first inauguration in 2000.
Kerry joked during a discussion at the World Economic Forum on Tuesday that Trump may not serve out his full term in office, and explained why he thought a Trump administration could not unilaterally pull out of the multinational nuclear deal with Iran.
"[Pulling out of the deal] will hurt for the endurance of a year, two years, whatever - while the administration is still there," Kerry said, drawing laughter from the crowd in Davos.
A senior State Department official told Fox