The actor appeared as the Earl of Manton in Julian Fellowes's ITV adaptation, which concluded in the UK and US on the 100th anniversary of the sinking last night (April 15).
Reflecting on the show, Roache claimed that there was never any rivalry with Cameron's Titanic blockbuster, which was rereleased in 3D at the same time the series aired.
"I had heard about the idea to tell the story of the whole ship," he recalled to The Hollywood Reporter. "We love the Cameron movie - it's brilliant and epic and romantic and delivers on so many levels.
"But this was playing on the story of all the different lives and like a microcosm of our culture and of 1912."
Roache also spoke of the unexpected obstacles that came with filming Titanic in the middle of a Hungarian summer.
He jested: "The only thing that was challenging was always running around a set in Budapest wearing a thick heavy winter coat in the middle of summer pretending to be freezing cold having just hit an iceberg when you've got sweat coming down your neck. That was not an expected acting challenge."
Fellowes said last month that he didn't want his Titanic to make villains out of passengers like the movie.
However, the £12m series has under-performed in the ratings - for which executive producer Nigel Stafford-Clarke this week accepted responsibility.
> 'Titanic' star: 'I was obsessed with Leonardo DiCaprio movie'