On his first day in the new position, chief executive Makoto Uchida also pledged to repair profitability at Japan's No. 2 automaker and said setting realistic targets would be key toward that goal, as it tries to make a clean break from the leadership of former chairman Carlos Ghosn.
"Closer capital ties with Renault are not a focus in the short term," he told reporters.
Uchida became CEO of Nissan on Dec. 1, as the car maker tries to recover from a profit slump and draw a line under a year of turmoil after the Ghosn scandal. The ousted chairman is fighting financial misconduct charges in Japan.
One of the new CEO's big tasks is to salvage ties with Renault, which have deteriorated since Ghosn's ouster as chairman of both companies.
Renault holds a 43.4% stake in Nissan after it saved the Japanese automaker from financial ruin two decades ago, and has pushed for the two companies to merge.
In rejecting a notion of a merger with Renault, Uchida, 53, echoes his predecessor Hiroto Saikawa, who stepped down in September.
He added that the alliance must re-think how it can serve all of its three members, which also includes Mitsubishi Motors.
"The alliance has to benefit each of its partners in terms of revenue and profit," he said.
"We need to re-evaluate what has worked and what hasn't worked in the alliance in the past few years."
The CEO called for Nissan to set "challenging but achievable" targets, adding that this and the launch of more new car models and vehicle technologies would be key to its financial recovery.
Nissan is bracing for its lowest annual profit in 11 years and has slashed its dividend by 65%. Its struggles come at a time when car companies desperately need scale to keep up with sweeping technological changes like electric vehicles and ride-hailing.
"Somewhere along the way we created a culture of setting targets which could not be achieved," Uchida said, adding that this had resulted in a focus on short-term results.
"Years of this had led Nissan to its current "difficult situation," he said, using heavy vehicle discounting in the U.S. market as an example of how aggressive sales targets to grow market share had deteriorated the company's brand.