Mr Coveney has previously hit out at Ms Truss in the row over the protocol and said that she was making “no effort” to resolve ongoing issues.
He also previously criticised the protocol row being used within the Conservative Party to generate support for leadership by Ms Truss.
“You have to differentiate between personal relationships and political responsibilities,” he told RTÉ’s This Week radio programme.
“We speak to each other plainly, or certainly we did when she was my counterpart.
“The approach that she decided to take as Foreign Secretary towards the protocol was, in my view, very unhelpful. It was an approach that I challenged, with her personally and that meant we had some difficult conversations. But that’s politics.”
Mr Coveney said Ms Truss had a “very strident” view in what she needed to achieve.
“She had a very strident view to what she believed she needed to do, and my job was to protect Irish interests.”
He said he met her in Westminster a couple of weeks ago and the relationship he has with her on a personal level as “very warm”.
He urged the UK to start a process of “serious and honest negotiation”.
Meanwhile, he refused to rule out a domestic price cap on energy prices as Budgetary discussions continue within Government next week.
“We will make a significant impact in terms of the pressure that families are feeling by spending a lot of money, which I think is justified,” he said.
This year’s entire multi billion surplus will not be spent on the cost of living package of one-off measures which will be announced alongside the Budget, according to the minister.
“We need to make sure that we respond immediately to the pressures that people face but also that we have some resources in reserve should these prices continue into next year.”