Micheal Martin has said he is confident ministers on both sides of the border can work together on Brexit and coronavirus.
During his first visit to Belfast as Taoiseach, Mr Martin met with the First and Deputy First Ministers in Stormont Castle, as well as the leaders of the smaller parties.
Despite renewed tension between the DUP and Sinn Fein over the Bobby Storey funeral, Arlene Foster and Michelle O'Neill appeared together for a picture with Mr Martin on his arrival.
Speaking afterwards, he said the wide-ranging discussions focused on suppressing any spikes in Covid-19 and minimising economic disruption caused by Brexit.
He quickly side-stepped a question on how the First and Deputy First Ministers could reconcile, saying: "I would never attempt to advise others in terms of relationship-building, but I think we had a very good, warm meeting today."
Stressing the need for all-Ireland cooperation, Mr Martin said the Good Friday Agreement would remain "the defining blueprint" in a post-Brexit world.
"Given the enormous change that is taking place, there is a need to do some significant work together in terms of... how we share the island in peace and in harmony," he said.
The Taoiseach said he was delighted that the first North-South Ministerial Council in three years will take place at the end of the month following the Stormont deadlock and disruption caused by Covid-19.
The body cooperates on areas such as the environment and waterways.
"Overall, I'm very encouraged by the meetings I've had... a genuine desire on all sides to work together in a pragmatic way to the mutual benefit of all the people of different traditions on this island," he said.
After years of strongly criticising Sinn Fein as Fianna Fail leader, Mr Martin was asked if he would now soften his approach in his new role.
"My views on Sinn Fein are well-known, I've articulated them as a party leader... but as Taoiseach one has to be very conscious of the objective of the country," he said.
He also played down any concerns over the different pace of lockdown on both sides of the border.
"Let's be fair to both administrations, Covid-19 has been suppressed to a significant degree," he said.
"That said, in the Republic over the last week or two we've had an increase in numbers, which the health officials are worried about."
He added: "All of us are very fearful of a second surge in the autumn, we're very anxious to get the schools back and to deal with the non-Covid strand of medicine."
Mrs Foster said she told the Taoiseach she looked forward to a positive dialogue during his tenure "based on mutual respect for both jurisdictions and understanding each other's differences".
Recovering from coronavirus had been the main focus of the meeting, she said, and working to rebuild both economies and protect public health. Mrs O'Neill called on Mr Martin to honour commitments made by the Irish Government in the New Decade, New Approach deal.
"I look forward to working on a north-south basis to ensure those crucial funding and practical commitments are fulfilled as soon as possible," she said.
She also backed recent calls to increase the use of mandatory face coverings in public.
"The Chief Medical Officer has made it very clear that while perhaps at one stage of this pandemic he was not convinced of the merits of face coverings, we are now in a space where he thinks that is the case.
"We will look at all of that evidence and then make a decision on that, but I think that as more and more people are moving around as we come to the end of the shielding period, there is probably a logical reason as to why face coverings should be a thing that we are all (forced to wear)."
Speaking to the media without Mrs Foster, she explained that they had "moved naturally" away from their joint appearances at the daily Stormont briefings.
Mrs O'Neill echoed the Taoiseach's call for an all-island approach to Covid-19, and said the two governments' chief medical advisers were working closely together.
Although Sinn Fein has now resumed the role of Opposition in the Dail, she promised to cooperate with the Taoiseach in his role as a co-guarantor of the Good Friday Agreement.
In a statement, she also stressed the importance of the North-South Ministerial Council returning to work after a lengthy absence.
"It is now six months since the restoration of the Executive and I made clear to Micheal that we must see delivery of all the Irish Government's commitments in New Decade, New Approach."