Donovan played for the US in the last three World Cups. He played an important role for the US team to win the 2013 CONCACAF Gold Cup and the World Cup qualifications, but his knee injury prevented him from reaching his top form, reports Xinhua.
"I was looking forward to playing in Brazil and, as you can imagine, I am very disappointed with today's decision," wrote Donovan on Twitter Thursday.
Klinsmann in a statement said that for the players it was very important to know that now they are a part of the squad and can relax.
"It's an exciting moment when you have narrowed the roster down as a coaching staff, and these 23 players that you've chosen can focus now purely on Brazil. We can go into more specific things about technical approaches, and about the opponents. For the players, it's very important to know that they are now part of it and they can relax and know they are on the list going to Brazil and taking it from there," the German said in a statement.
The US would play Azerbaijan ,Turkey and Nigeria before the World Cup.
Goalkeepers: Brad Guzan (Aston Villa), Tim Howard (Everton), Nick Rimando (Real Salt Lake)
Defenders: DaMarcus Beasley (Puebla), Matt Besler (Sporting Kansas City), John Brooks (Hertha Berlin), Geoff Cameron (Stoke City), Timmy Chandler (Nurnberg), Omar Gonzalez (LA Galaxy), Fabian Johnson (Borussia Monchengladbach), DeAndre Yedlin (Seattle Sounders FC)
Midfielders: Kyle Beckerman (Real Salt Lake), Alejandro Bedoya (Nantes), Michael Bradley (Toronto FC), Brad Davis (Houston Dynamo), Mix Diskerud (Rosenborg), Julian Green (Bayern Munich), Jermaine Jones (Besiktas), Graham Zusi (Sporting Kansas City)
Forwards: Jozy Altidore (Sunderland), Clint Dempsey (Seattle Sounders FC), Aron Johannsson (AZ Alkmaar), Chris Wondolowski (San Jose Earthquakes)