Haas are leaving their driver lineup for the 2017 season open for now.
"It is not true that I went to Haas only because of Ferrari," the Frenchman, referring to Haas's close technical partner, is quoted by as saying by Speed Week.
"I see this as a long-term project."
Esteban Gutierrez, Ferrari's former reserve driver, is similarly linked with the works team as are his Mexican backers, but his future seems less clear than Grosjean's.
Haas team boss Gunther Steiner said: "We have agreed to only talk about the driver lineup after all of the races in Europe."
F1's next four grands prix are all in Europe - in Hungary, Germany, Belgium, and finally the Italian Grand Prix at Monza in early September.
As for Gutierrez, Steiner commented: "It wouldn't be fair to judge Esteban only on the first half of the season, because there were some races where he was let down.
"We are under no pressure. We are also not negotiating with anyone, because we want to avoid speculation and uncertainty. The drivers should be able to do their performance with the best possible atmosphere."
Grosjean has been responsible for all 28 of the team's points so far in 2016.