"Whilst our preference would have been to race in Miami in 2019, there was always a point by which delivering the best possible wheel-to-wheel racing experience for our fans, drivers and teams wouldn't be possible in the time available," F1 commercial manager Sean Bratches said in a statement.
"We have now reached that point as far as racing in Miami in 2019 is concerned.
"However, we are taking a long-term view and, as a result, we have decided, in consultation with the Miami authorities, to postpone sign-off until later in the summer, with the aim of running the first Formula 1 Miami Grand Prix in the 2020 season."
Formula One's commercial rights holders Liberty Media are keen to expand in the United States, whose only race at present is at the Circuit of the Americas in Austin, Texas.
Liberty want to make sure Miami, which has been offered a 10-year contract, has long-term viability with the maximum local support.
Bratches added that Formula One would stage one of its "fan festivals" in Miami in October, when teams will engage with the fans.
(Reporting by Hardik Vyas in Bengaluru; Editing by Ken Ferris)
