Knicks president Phil Jackson claims he warned the Lakers they’d be sorry if they passed on Kristaps Porzingis at No. 2 in last June’s draft.

The Lakers instead selected point guard D’Angelo Russell, who had an up-and-down rookie year. The 7-foot-3 Porzingis fell to the Knicks at No. 4 and finished runner-up in the Rookie of the Year voting.

In excerpts obtained from MSG Network from its special airing Wednesday night on the Jeff Hornacek hiring, Jackson said: “We knew that [Porzingis] had a lot of talent. We saw that even in the workout with him shooting, and I had some fun with one of the Buss guys and I told him after [our] workout, ‘You guys are going to be sorry if you don’t pick up Porzingis with the second pick.’ They didn’t, we did.”

Jackson’s remark was a shot back at the Lakers, whose ex-coach Byron Scott said last month they passed on Porzingis because he looked out of shape in his L.A. workout.

Jackson’s fiancée is Lakers president Jeanie Buss, whose older brother Jimmy Buss is the team’s vice president of basketball operations.

“Watching him in the summer league, we thought he was really competitive, that’s what we wanted to see in the tapes study we did,’’ Jackson added. “But when we saw that he had the stamina to play 28 to 32 minutes, well, we thought maybe he was going to be a 20-to-22-minute guy because of his strength and his lack of size or weight. But we knew how competitive, and what an athletic talent he was, really to be able to have that stamina.’’

In the MSG Network special, Jackson went on to say there will be “no boundaries’’ between him and Hornacek in terms of giving his input. Jackson admitted that in Derek Fisher’s rookie year, he stepped back, hoping Fisher would rely on his experienced assistant coaches such as Kurt Rambis and Jim Cleamons. Fisher got fired in February, according to a source, for not communicating well with Jackson.

“One of the things that distinguished the relationship that I had with Derek is that perhaps I anticipated that the support staff that he had with him was going to be really influential in his learning experience, and [I was] trying to stay away from him because there was so much attention about he was one of my former players and he hadn’t been a coach,’’ Jackson said. “So my input was limited. Last year I started having more input in the relationship. … That’s the thing that I really think makes sense for good organizations — is that there are no boundaries between the coach, general manager, and president.

“If someone’s got something to contribute, then we want to hear it, we want to bring it up. We’ve got a video guy that’s coming to us and saying, ‘You gotta look at this’ — this is what we think is important, it should happen. We want to have an open opportunity for them to express that. So those are things that are really important.”

Ironically, Jackson set boundaries when he was coach of the Bulls and Lakers, getting into wars with GMs Jerry Krause and Jerry West, respectively.

MSG Network’s special is called “Jeff Hornacek: A Knicks Beginning” and airs at 6:30 p.m. Jackson, Hornacek and general manager Steve Mills give their insights into the shocking hiring.