Taoiseach Micheál Martin has said the Irish Government is seeking flexibility from the EU on VAT on fuels in order to further ease the burden on consumers.
Arriving at the two-day EU Summit in Versailles, Mr Martin said Ireland would not want to lose its historic derogations on VAT in other areas.
"This basically means that we are at a lower rate now and if we reduce VAT even further, returning when things go back to normal, we would have to go back to a higher rate."
He said any price gouging following the excise cut was "morally reprehensible" in the context of a barbaric war and he called on it to cease.
He said that if people had evidence of price fixing, they should bring it to the authorities.
On defence, he did not rule out sending Irish forces to the fringes of Ukraine although he said any decision on that would be subject to the triple lock mechanism.
Over the course of the two-day summit, EU leaders will discuss weaning the bloc off Russian energy in the face of Moscow's war in Ukraine, but internal divisions and fear of provoking President Vladimir Putin mean they will not invite Kyiv to join the bloc.
Mr Martin is among the 27 national EU leaders gathering in France's Versailles palace, and they will discuss looking at shoring up EU defences and economies.
As things stand, they are set to disappoint Ukraine's dramatic appeal for quick membership as the country battles Russian invasion.
EU leaders arriving now at Versailles pic.twitter.com/g2RlEGkmfL— Sandra Hurley (@sandra_hurley) March 10, 2022
"It will take time," French European Affairs Minister Clement Beaune told France Inter radio, adding that Ukraine's accession to the EU was "not for tomorrow".
Russia's 24 February military invasion shattered Europe's security order that emerged from the ashes of World War II and the collapse of the Soviet Union in 1991.
Belgian Prime Minister Alexander de Croo said Europe was facing its 11 September moment, a reference to the 2001 al-Qaeda attacks on the United States that triggered a Washington-led invasion of Afghanistan and years of a so-called international "war on terror".
"We are not taking part but it is on our doorstep," Mr de Croo told the Le Soir daily, referring to Russia's assault on Ukraine.
"September 11 was a decisive moment in the United States. This war in Ukraine is Europe's 9/11."
The EU has implemented sanctions of unprecedented severity on Russia for invading its neighbour, including cutting seven Russian banks from the SWIFT transaction system, targeting Moscow ally Belarus and blacklisting Russian state officials and billionaire oligarchs close to the Kremlin.
'Tectonic shift in European history'
In a draft declaration, EU leaders were expected to say: "Russia's war of aggression constitutes a tectonic shift in European history," adding that the invasion confronted them with "growing instability, strategic competition and security threats".
The EU still pays hundreds of millions of US dollars every day to Russia, its biggest energy supplier, for more than 40% of its natural gas, more than a quarter of oil imports and almost half of its coal.
While the United States has already cut Russian oil imports, the case for the EU is viewed as more complicated, expensive and politically sensitive as it fears further big jumps in energy and food prices.
EU leaders disagree on a deadline for jettisoning Russian energy sources because national dependency differs, with Germany, Italy, Hungary and Austria being the most exposed.
Russia hawks in the EU including Poland and Lithuania – both once under Soviet domination from Moscow - want to punish Vladimir Putin harder and say the West should be ready to bear the price of retaliation. But Germany, France and some western EU states want to keep on doing business.
EU nations are just as split on letting Ukraine join their affluent union, with France and the Netherlands leading the reluctant camp against a group of strong supporters including Poland and other eastern EU neighbours of Ukraine.
Both sanctions and enlargement - a process that normally takes years to satisfy strict criteria ranging from economic stability to rooting out corruption and respecting liberal human rights - require unanimity in the EU.
Ukraine is a former Soviet republic that now wants to join the EU and NATO. That is anathema to Moscow where Mr Putin launched what he calls a "special military operation" to derail Ukraine's drive for deeper integration with Western democracies.
Russian forces have bombarded Ukrainian cities and sent more than two million refugees fleeing into the EU. Kyiv has appealed for more Western help beyond economic sanctions and some arms supplies.
But, wary of the economic hit as well as being dragged directly into the war, the EU is more likely to offer words of moral support to Ukraine, as it looks inwards to get ready for years of worsening confrontation with Russia.
Additional reporting Reuters