The Minister for Foreign Affairs says he hopes there is not a repeat of Saturday's protest in West Dublin which saw the Tánaiste Joan Burton trapped in her car for over two hours.
Yesterday, a member of the Anti-Austerity Alliance, Deputy Paul Murphy, who was one of the organisers of Saturday's anti-water charges demonstration, defended it as being peaceful and said the Tánaiste was not in any danger.
Charlie Flanagan says people have the right to peaceful protest, but it must be within the law.
He said: "I think it's absolutely essential that on all occasions protest is within the law and within our public order legislation.
"It seems to me that the situation for the Tánaiste was scary, was frightening and I hope there is not a repetition.
"In any democracy there is a right for the public to engage in opposition and peaceful protest."