MOSCOW—Russia, in its first detailed version of events surrounding the final minutes of Malaysia Airlines Flight 17, dismissed accusations that pro-Moscow rebels shot down the plane, instead suggesting that a Ukrainian fighter plane or missile systems could have been involved.

The elaborate, televised Defense Ministry presentation—at odds with Western and Ukrainian accusations that Kremlin-backed insurgents shot down the plane—came as the U.S. and Russia clashed at the U.N. Security Council on Monday. There, both countries...