Campaign Co-Director Ailbhe Smyth said of the ban: "We welcome confirmation today from Google that they are going to stop running political advertisements over the next 24 hours".
The referendum, being held on 25 May, could repeal the Republic's Eighth Amendment, which now upholds a near-total ban on abortions.
The referendum is due to take place on May 25.
"We're suddenly being told that we will no longer be allowed to speak to voters on our channels, and we think that is outrageous", McGuirk said.
TECH GIANTS Google and YouTube have declared that they will ban all ads relating to the upcoming referendum on abortion.
The polls have narrowed, the text reads, and "clearly there is fear in establishment Ireland" that this referendum will be defeated.
They also said that the action from Google was taken because one side of the referendum was afraid it is "losing" the campaign, and said that "massive pressure" had been exerted on the online companies from the government, media and Yes side to take action against adverts on the campaign.
The move won't impact on content or search results that are returned by Google searches.
"What is happening here is not about one side or the other, it's about democracy and transparency", Higgins said.
The group claims that it will now be put at a disadvantage because it had particularly relied on posters and social media to put out its message. Although Irish law bans foreign donations to political campaigns, there had been concerns that overseas campaigners were still able to spend potentially unlimited sums buying adverts targeting Irish voters.
It was clear from the outset that this referendum would be a playground for the much-maligned tactics used in the Trump and Brexit campaigns (Aaron Rogan writes).
Mr Lawless has been pushing for a law requiring all online advertisers to disclose the publishers and sponsors behind ads.