Anti-Austerity Alliance TD Paul Murphy has called on the protesters who shouted insults at President Higgins to apologise.
Video footage emerged yesterday showing anti-water charge demonstrators shouted "midget", "traitor" and "parasite" at Michael D Higgins during a visit to a school in Finglas in Dublin last week.
There has been widespread condemnation of the protesters' actions - with the Taoiseach calling the incident "deplorable".
Deputy Murphy says he believes that he knows the people responsible - and said that they should apologise to the President.
"I think they should apologise for using personal abuse, for the names that they called him," he said.
"That's inappropriate, it doesn't add anything to the cause against the water charges.
"I think I know who they were, I think I've seen them on previous protests.
"I don't have their phone numbers, and couldn't pick up the phone to ring them, no."