The clip also shows the Wakandan army, led by Black Panther, preparing for battle against Thanos and his army.
Fans went crazy and took to Twitter, reacting to the new trailer.
One user wrote,"Cap and Bucky I'm in tears"
"Marvel dropped a new Avengers out of nowhere. It's so good to see more of the Wakandans and Bucky and Cap have a moment," wrote another.
One user tweeted,"Cap and Bucky are in love and Thanos can't stop them."
Directed by Anthony Russo and Joe Russo, the film is scheduled for an April 27 release.