Matthew Waine made his remarks during consideration of a motion to adopt the practice at the Swords headquarters of Fingal County Council, one of four councils in Dublin region.
Mr Waine, who represents Solidarity – People Before Profit believed flying Ireland’s tricolour risked alienating people from other countries living there.
He said: “We have one of the most multi-cultural populations in the whole country living in Fingal, and I think we need to consider the sensitivity of this.
“The issue of religion, language, nationality – all of those issues are extremely sensitive and we’ve seen how that can play out to divide people.
“I would prefer to see the flagpoles used to express solidarity, so for example on the week of Pride, we should show the Rainbow flag.
“I think we should fly the flags of minority groups, like Pavee Point.
“I come from the tradition of the workers’ movement which doesn’t see the country of your birth as being anything significant.
“I would prefer to see the red flag fly outside County Hall, and maybe in the future that will be the case.”
Independent councillor David O’Connor said: “You’re saying what a lot of people think.”
He also won support from Fine Gael’s Councillor Brian Dennehy, who said flags cold be “used as a wedge to divide people”.
However, Fianna Fail’s Darragh Butler said: “I think it’s staggering that a councillor should say we shouldn’t fly our national flag, or hide our own flag away.”
Meanwhile Jimmy Guerin, another independent councillor, said: “I take offence at the comments of Cllr Waine. I’m not surprised at him.”
Councillor Ni Laoi said: “I’d love to see the national flag flying from the turrets of Malahide Castle and Swords Castle and Ardgillen.
“But for now I’m just proposing that this flag, this symbol of tolerance, inclusion and respect, be flown outside County Hall.”
The motion was eventually carried by 34 votes to two.
Ireland’s distinctive vertical tricolour consists of three equal brands of green, white and orange.
It was originally presented to Irish national Thomas Francis Meagre from a group of French woman in 1848, and is intended to symbolise a union between Roman Catholics and Protestants.
The white in the middle signifies a lasting peace between the two.
It was not until the flag was raised above Dublin’s General Post Office during the Easter Rising of 1916 that the tricolour came to be regarded as the country’s national flag.
The flag was officially adopted by the Irish Republic during the Irish War of Independence in 1919, and was finally afforded constitutional status in accordance with the 1937 Constitution of Ireland.