Rossi lost out race seat in Manor to Indonesia backed Rio Haryanto
Rossi raced with the team last season but couldn't score a point.
American Alexander Rossi said he lost his chance of racing for Manor in Formula One this season because Rio Haryanto's Indonesian backers offered the team more money.
"I always knew going up against a country was going to be impossible," the Californian, who raced for the team in five Grands Prix last year, told racer.com.
"We couldn't match some of what they were willing to do and sign, and (Indonesia) really wanted him to be there, so more power to them."
Haryanto was confirmed by the team on Thursday.
Manor, who competed as Marussia last year and have the smallest budget in the sport, have always been open in the past about the need for their drivers to bring sponsorship or financial backing in order to secure the seat.
The tail-end team went into administration at the end of the 2014 season, before emerging under new ownership, and money remains tight.
Wehrlein joins Manor
The team's other driver is Mercedes reserve Pascal Wehrlein, with the German manufacturer and reigning champions also providing the team's engines.
Rossi said he always knew it would be a struggle to stay with the team.
"When Wehrlein was announced, that put the pressure on us to be in an auction for the second seat. We thought we had an agreement, and the money was good for (Manor) up until about a week ago," he said.
"Then they said we needed a couple million more, which was an effort, but we were able to find it. And then when we went back to meet with them with that number, they said they were very sorry but Haryanto had doubled his offer."
Haryanto is backed primarily by Indonesian state oil and gas company Pertamina, whose chief executive said on Thursday they had contributed five million euros ($5.55 million) towards securing the seat.
The driver's manager Piers Hunnisett said more Indonesian companies were interested in sponsoring Haryanto, as were others from Japan and Malaysia, but gave no details.
Rossi said he would now assess his options in IndyCar and the World Endurance Championship among other series.