The Tourism Minister Paschal Donohoe says he is "absolutely against" the proposal for restaurants to charge a euro for a glass of tap water.
The Restaurants Association of Ireland has indicated the charges are likely to be introduced next year, because of expected hikes in commercial water rates.
However, Minister Donohoe says that would be bad for Ireland's image, both here and abroad.
He said: "I'm absolutely against that happening. The restaurants know better than anybody else that what we need to do is continue delivering good value for money.
"Ireland has made great progress in recent years in regaining a perception for being good value to come to Ireland to eat out and enjoy yourself.
"We cannot be complacent at all about maintaining that reputation, and we have to resist anything at all that could result in that reputation being damaged."