The tourists came away from the breathtaking ground at Dharamsala with a seven-wicket success after Ian Bell carried his bat in the second innings for a match-winning 113 not out. Bell faced 143 balls, hit 13 fours and one six as he carried England over the line, while Tim Bresnan took the bowling honours with four for 45 as India were dismissed for 226.
Cook was full of praise for his side's efforts in the final match, but was mindful not to let the result overshadow the three defeats that came before it. "We're not really in it for 'decent efforts'," he said.
"It was very important to end the series on a high but there's always disappointment when you come to try and win a series then lose 3-2. We've had a really good couple of years in ODIs, so of course we're a little bit disappointed in the result of the series.
"It's probably a little frustrating. I said at the start of the tour that when we play to our potential we win games, and when we have played well here we've put India under some pressure. Obviously in a couple of games we didn't do that."
England's next assignment is just around the corner, with the first Twenty20 warm-up in New Zealand taking place on February 4. Cook will not join up with the side until the ODI matches later in the month but he feels the travelling party will be in good hands.
Ashley Giles has now overseen his first series as limited-overs coach and will be boosted in New Zealand by the return of Stuart Broad, Jonathan Trott, James Anderson and Graeme Swann. Cook added: "One thing we take away is obviously the relationship with Ashley in his first series as coach.
"All the players have been getting to know him and his methods and that will only grow as time goes on. It's been a young squad out here and with the senior lads coming back now that adds a lot of competition for places. We take a lot through to New Zealand from this month."
India captain Mahendra Singh Dhoni was not in the mood for celebrating despite registering a series win to avenge the Test defeat before Christmas, and focused on areas that need to improve.
"We should have won this game; maybe we should have batted more sensibly," he said. "It is a young side and it will learn with time. Thankfully, in three games, we didn't have to bowl those death overs, and that remains an area of concern."