But not all leaders heeded his call at the two-day EU summit in Brussels and French President Jacques Chirac skipped a lunch hosted by the EU leaders for Allawi on Friday.
France was the most outspoken critic of last year's US-led war on Iraq and relations with the interim government in Baghdad have been chilly.
But Chirac insisted he was not snubbing Allawi.
Europe was deeply split by the Iraq war, with an anti-war group led by France and Germany standing against a pro-US camp spearheaded by British Prime Minister Tony Blair.
But the 25-strong bloc is trying to unite behind the reconstruction of the country. EU leaders endorsed the immediate release of a limited aid package of $39 million to support the election process before Iraqi polls planned for January.
US President George Bush has welcomed aid given by the EU to Iraq.
"The United States especially welcomes the EU's reaffirmation today of its commitment to assist in the emergence of a stable, secure and democratic Iraq," said White House spokesman Scott McClellan.
"These steps are all important investments in Iraq's future".