The ex-Hollyoaks actor is facing charges of dangerous driving over an alleged collision with Farrell in Liverpool in the early morning of November 27 last year.
Whittle was collecting his ex-girlfriend Carley Stenson and a friend from a party in his red Dodge Ram truck when they were followed by a group of photographers hoping to get a picture of the soap stars together.
Prosecutors have claimed that Whittle hit Farrell out of "irritation".
Speaking in court yesterday, Whittle said: "I said [to the photographers], 'life's s**t as it is, can you give us a break? It's cold and the girls are only in dresses, just leave us alone'."
He said that one photographer put down his camera, but Farrell persisted on taking pictures. Whittle also claimed that he was forced to cover his eyes because of the bright night flash the paparazzo was using.
"I revved my engine, indicating that I wanted to move the car away," he said. "I was using the frame of the car between the windscreen and the driver-side door to shield from the flash. I was aware the road ahead was clear so I put the car in gear and escaped."
He told the court that he had not realised he had swerved and hit Farrell until he was arrested. He admitted that he heard a "clunk" noise, but claimed that he originally thought it was just the photographer's camera hitting his vehicle.
Stenson will give her evidence in court today.