Question

how antony able to provoke the roman mob against

Answer 1

He was a good speaker. Using ironic and sarcastic tone, he appealed to the emotions of the people listening to him.
He gave them time to form right opinions and think properly

Answer 2

Antony had delivered a speech on funeral of Caesar and with his powerful words the mob knew the truth of the Brutus and other conspirators this provoked the mob.