The Battleship star revealed that he had not known Lively for long before they were asked to film the intimate moments, People reports.
"A lot of sexual improv was going on there," he said. "God knows we had two weeks of rehearsal, so we talked until we were about to pass out, and then [we shot the sex scenes] on the day I think I knew Blake three days... four days maybe."
Kitsch also suggested that the sex scenes are very important with regards to his character.
"It's very awkward to do, you know, and I was just glad it was over with to be honest," he said. "And it's such a big part of [my character] and who he is, and that's how you meet him. So it's a pretty intense reveal, no pun intended."
Savages is due in theaters on July 6 in the US and on September 28 in the UK.
Watch a Savages character trailer featuring Taylor Kitsch below: