I think that Antony seems a bit unnerved in this scene. In the beginning, he tells Octavius that they should attack on the left flank. Octavius disagrees saying they will attack on the right. Antony asks Octavius why he is going against him because he is obviously the more experienced soldier, but Octavius is firm in his decision. He is already acting like a "Caesar" and a few lines later, Antony calls him "Caesar" - leader.
Later, Antony and Octavius talk with Brutus and Cassius and Antony is emotional. When he recalls how Caesar was killed, he tells Brutus and Cassius:
Villains, you didn’t think so when your vile daggers
Hacked one another into the sides of Caesar.
You showed your teeth like apes, and wagged your tails
Like hounds, and bowed like slaves, kissing Caesar's feet;
While damned Casca, like a wild dog, struck Caesar
From behind on the neck. O flatterers!
He gets himself so worked up that Octavius must lead him away, saying:
Come, Antony; away!—
We hurl “Defiance, traitors,” in your teeth.
If you dare to fight today, come to the field;
If not, come when you’ve got stomachs
Antony shows he is still mourning Caesar's death and is determined to avenge his friend.
You can read the text here on eNotes and see if you agree.