The pair, two of coach Fernando Santos' most senior players among his 23-man squad, almost came to blows in controversial circumstances in a tense Greek Cup semi-final last month.
PAOK midfielder Katsouranis, 34, was sent-off in the April 16 match against Maniatis' Olympiakos, and both players had to be separated after the final whistle as scuffles broke out.
"We have talked about it a lot and I think it was a mistake from all aspects," Katsouranis told reporters.
"As vice captain of the team and one of the most senior players who has been in the squad since Euro 2004, I think I have a large responsibility, I was in the wrong and I have explained this to Giannis many times."
It is the first time Katsouranis, who has made 109 appearances for his country, has spoken publicly about the incident and he said there were no hard feelings.
"We need to stick together. Sometimes you lose control and I think that since making my national team debut in 2003 I've never had such an issue. In football these things can happen but we will continue as we were before," he said.
Greece striker Fanis Gekas also sought to allay the notion held by local media that the episode exposed an unhealthy atmosphere in the squad on the eve of their departure for Brazil.
"There are no worries. The climate is and will be good. We are like a family and everything depends on our attitude," he said.
"If we play as we can and are well organised, we have all the quality, experience and character to at least qualify from the group stage."
Greece face Colombia, Ivory Coast and Japan in Group C in Brazil, their first match against the South Americans is on June 14 in Belo Horizonte.
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