The Spaniard, who lost the numero uno tag to Federer earlier this month, also said his arch-rival "deserves" the position, given his consistent results in 2017.
Federer was ranked 17 at the start of last season. The Swiss legend proved age is just a number by winning seven titles in 2017, including the Australian Open weeks after his return from a six-month injury layoff.
Cut to February 2018, the 36-year-old became the oldest world number one, following his successful title defense at Australian Open and dominant win at Rotterdam Open.
"I am not going to fight for that, I am going to do my calendar and then we will see what is going on," Nadal told ATP's official website during a video interview.
"But yeah, he [Federer] is great. Incredible to see him back to world number one. Congrats to him. he did so well last year. He deserves it," he added.
The 16-time Grand Slam winner will not be able to dethrone Federer in ATP rankings but the two might be involved a direct battle at the season's first Masters 1000 tournament in Indian Wells, starting March 8.
Nadal will start as the top seed at the ongoing ATP 500 tournament. He will face compatriot Feliciano Lopez in the first round on Wednesday, February 28.
The world number two, who is looking set to win his third title in Acapulco, said he is "ready" after a successful recovery from the hip injury.
"I took a couple of weeks of rest and worked hard on rehabilitation. Last week I started practicing hard again. I feel ready. Injuries are part of my career. It's not the first time," Nadal said, as quoted by AFP.
"Of course it's tough, especially at this point when you feel ready to compete well. For me, it was a good chance to be fighting for an important title in Australia. But it happened and I can't complain."