"To call this a wall would be wrong. It is only a barrier. We discussed the issue and we have full confidence in each other," Prime Minister Recep Tayyip Erdogan said at a televised news conference with his Greek counterpart George Papandreou.
The two leaders met in the eastern Turkish city of Erzurum, where Papandreou attended as a guest a conference of senior Turkish diplomats.
Erdogan said he was impressed to learn that Greece currently hosted about one million illigal immigrants, most of whom reached the country through Turkey.
"The figures are very, very high and they influenced my opinion," he said.
Papandreou stressed the barrier plan did not target Turkish citizens.
"We are speaking about a common problem.... We cooperate on this problem and we had a very constructive discussion," he said through an interpreter.
"I am confident we will take our cooperation farther.... We have to convince the Europeans that we have a very serious and close cooperation with Turkey on the problem of illegal immigration," he added.
Athens has said it will "put in place means to push back illegal migrants," on a stretch of 12.5 kilometres (eight miles) of the border with Turkey, which it describes as totally unprotected.
The European Union has expressed misgivings that Greece's plan would be only a short-term measure.
The UN High Commissioner for Refugees has repeatedly urged Greece to ensure its efforts to fight illegal immigration do not harm legitimate asylum-seekers, including Afghans, Iraqis and Somalis.
The targeted zone has become the main entry point for illegal border crossings.
More than 200 guards with European border agency Frontex were deployed in the area in November, which the agency said led to a 44-percent drop in the number of clandestine entries.
Illegal immigrants from Africa and Asia are rounded up on a daily basis also in Turkey, which lies on a major human-smuggling route from Asia to Europe.
Deadly accidents are frequent as the traffickers often use unseaworthy vessels to sail the illegals to Greek islands facing the Turkish shore or to mainland Greece across the Maritza river, which forms the border between the two countries.