Shatter understands people's anger and upset
Mr Shatter said he understands people are "angry and upset" by decisions made by former taoiseach Mr Ahern and his Government, but it is important that they obey the law.
"There are tens of thousands of people in this country suffering the consequences of decisions made," he said.
"But that doesn't mean that any member of any previous Government should be the object of any physical attack or any unlawful conduct by any individual."
Mr Shatter said people have the right to go about their lives and that gardai will act appropriately should anyone act unlawfully
He said he would in no way condone "any individual being the object of any assault".
The minister rejected any suggestion that the removal of Garda cars from former taoisigh in 2011 had anything to do with the alleged attack on Mr Ahern.
"I don't think any of these issues that I have been reading about have any relevance to anybody being driven anywhere," he said.
He added: "At an early stage in the lifetime of this Government a decision was made that it wasn't necessary for the State on an ongoing basis to provide a car and a Garda driver to former taoisigh.
"The decision was made to withdraw the facility from former taoisigh."