Ken Marsh, Chair of the Metropolitan Police Federation, said: "We are pleased to hear this verdict... but frankly this case should never have got to court.
"It's perverse that a Police Officer doing the job the public would expect - namely courageously heading towards the danger of a terrorist attack, could find themselves in the dock with their career on the line.
"Let's remember our colleagues put their lives in danger that day to protect the public. It is what we do.
"The public will rightly be appalled that brave police officers responding to a terrorist attack can be treated in such a manner.
"We must do better. Or we risk a society where police officers will be left questioning whether they should head towards that danger. That potential hesitation - caused by the hindsight brigade - will cost lives.
"That can't be right.
"We now ask that PC Paul Fisher is allowed to carry on his career and do the job the public expect of him."