Yusuke Hasegawa says Honda remains "100 per cent committed" to McLaren, amid reports that the team have approached Mercedes over switching engine suppliers.
After a disappointing comeback with McLaren in 2015, Honda saw improvement last year, though results were still considered sub-par.
Pre-season has given more cause for concern, with the Woking-based team blighted with issues across two tests in Barcelona and racing director Eric Boullier said relations were under "maximum" strain.
Reports emerged that McLaren were attempting to strike up a deal for Mercedes to become their new power-unit provider, but Hasegawa is not considering a potential change in terms.
"Of course the situation we find ourselves in is not what we hoped for when we returned to Formula One, but we are still 100 per cent committed to our future in the sport and our relationship with McLaren," Hasegawa told Motorsport.com.
"We believe in this partnership, as does McLaren, and in order to move forward it is important for us to work as one team and overcome the situation together.
"The priority is to maintain honest and open communication, and to continue strengthening all relationships between Honda and McLaren despite the difficulties we are facing.
"This is not a short-term project for us."