So far almost 2,000 children have been detained at the US-Mexican border between April and the end of May.
The policy has been described as "nothing short of torture" by Amnesty International.
The head of Amnesty International Ireland, Colm O'Gorman is urging people to attend the protest on Thursday. "Please come along and make your voice heard," he said.
Meanwhile, the Irish government is now planning to convey its "grave concern" over the policy to the US Ambassador.
The government has also agreed to debate a cross-party motion condemning the US action on Thursday.
Leo Varadkar warned that America “is more and more departing from its own values”.
Leo added: “We know from dark chapters in our own history the consequences of separating children from their parents and how that lasted them for their entire lives and damaged them for their entire lives.”
Also, a Fine Gael TD has expressed his concern and horror with the United States embassy in Ireland over the Trump policy.
TD Alan Farrell has told us that he wrote on Tuesday to Reece Smyth, Chargé d’Affaires, US Embassy in Dublin informing him of his "concern and horror" with regard to the treatment of children at the border.

Protest against US policy of separating children from their parents and detaining them at @USEmbassyDublin from 4pm this Thursday. Please come along and make your voice heard. https://t.co/pLY3Ipl8L1

— Colm O'Gorman (@Colmogorman) June 19, 2018

Dublin Fingal TD and Chair of the Oireachtas Children and Youth Affairs Committee Alan Farrell said: “The images from Texas and the US borders of tearful children being separated from their parents has left me horrified.
“As a father to two small boys and as Chair of the Oireachtas Children and Youth Affairs Committee, I can only imagine the turmoil that those separated families are currently going through. It is absolutely, utterly heart-breaking.
“As publically elected representatives, we, in time, will be judged by our responses to events that provoke anger, horror or fear.
"The images emerging from the US-Mexican border and of children being held in cages have invoked fear and horror worldwide. We, have an immediate duty to respond, in an appropriate fashion.
He added: “Humane treatment does not require a Visa and the so called ‘land of the free’, the US must do better than this. This policy, adopted by the current US administration, casts an appalling shadow over the US.
"The treatment of families and innocent children in this way is barbaric and traumatising. It cannot be ignored or pushed away with a dismissive, misdirecting tweet.
"As a country with a long history of emigration, particularly to the United States, those who left our shores in search of a better future elsewhere were not subject to the barbaric treatment we see today when they reached Ellis Island.
"Given our history, we have an obligation to those who have gone before us to speak out when we see such injustices and ill-treatment of emigrants today."
Fianna Fáil TD for Cavan Monaghan and Chairman of the Joint Committee on Foreign Affairs, Trade and Defence, Brendan Smith TD has also expressed his condemnation of the policy and will request the Joint Committee formally support his position on these actions at its meeting on Thursday next, 21st June.
Commenting ahead of the meeting Deputy Smith said, “The policy now being implemented by the US Administration of separating immigrant children from their parents at the US-Mexico border is something that needs to stop with immediate effect. The images of frightened children, separated from their parents and being held in cages has shocked the world and is reminiscent to some of the darkest days in history.
"As a civilised society we cannot allow this practice to continue and we must express our utter condemnation.
“On Thursday I will ask the Joint Committee on Foreign Affairs, Trade and Defence to support me in condemning this practice and to formally convey to the US Chargé d’Affaires to Ireland the very deep concerns of the Joint Committee and to call for an immediate cessation to this practice,” he concluded.
While Fianna Fáil Spokesperson on Foreign Affairs and Trade Niall Collins TD has said that the US immigration policy of separating children from their parents is "cruel, inhumane and unacceptable".
Deputy Collins said: “I am appalled by the US immigration policy whereby children are being separated from their parents.
"The images emerging of children being detained in what are effectively cages underscores the cruelty and inhumanity of this policy. I believe that America can and must do better.
“Using children as bargaining chips is something that no humane and decent society should countenance. It’s beyond the pale and, as a father; I am deeply concerned that it sets a new precedent.
“I am also calling on the Tánaiste and the Minister for Foreign Affairs and Trade, Simon Coveney to formally relay our revulsion to this policy to the US administration. Ireland must formally add its voice to the global chorus of nations calling for an end to this ill-conceived and heartless policy.
“On behalf of Fianna Fáil, I also intend to raise this issue with the US Embassy when I meet them on Thursday,” concluded Collins.