The NUJ has condemned the attack on Belfast Telegraph journalist Adrian Rutherford.
Mr Rutherford was attacked and had his phone stolen by a masked gang while covering Loyalist protests in East Belfast on Monday night.
Séamus Dooley, Irish Secretary said the assault on Mr Rutherford was the latest in a series of attacks on journalists in Northern Ireland.
Mr Dooley said: “This is an extremely worrying development. Attacks of this type against reporters and photographers represent an attack on democracy, in the same way as attacks and threats against elected public representatives strike at the heart of democracy.
"No one disputes the right of citizens or groups to engage in legitimate protests but recent days have been marked by unacceptable behaviour which seeks to intimidate and terrorise innocent people going about their work in the public interest. I would appeal to all those in positions of influence to unite against this type of behaviour and to work towards creating a safe environment for all communities.”
The attack has been strongly condemned by the NUJ Belfast and District branch, which incorporates the Belfast Telegraph.
In a statement the branch said: “This was yet another in a growing catalogue of attacks and threats to journalists by people who continue to indulge in unacceptable behaviour - activity condemned by the leaders of all mainstream parties.
“The NUJ calls for an end to attacks on journalists and urges all political representatives to see such attacks as an assault on democracy and to endorse the NUJ’s call."
The Northern Ireland Human Rights Chief Commissioner has expressed deep concern over recent attacks on journalists in Northern Ireland.
NIHRC Chief Commissioner Professor Michael O'Flaherty commented:
"There has been a disturbing number of attacks carried out on members of the press in Northern Ireland over the past few weeks, I strongly condemn these, including the most recent attack endured by Belfast Telegraph Journalist Adrian Rutherford. Such acts are intolerable and they risk the most important of all human rights, the right to life.
"This situation occurs alongside a worrying practice globally of journalists being killed in the course of their vital work. Figures released yesterday by Reporters Without Borders indicate that 88 journalists were killed in 2012, a third more than in 2011. It is a fact that human rights cannot thrive without a free press, and the public interest is often maintained by those on the frontline of reporting.
"United Nations human rights guidance is clear: 'A free, uncensored and unhindered press or other media is essential in any society to ensure freedom of opinion and expression and the enjoyment of other [human] rights. It constitutes one of the cornerstones of a democratic society'."