The transport secretary said that he understood the "frustration" of Britain's rail passengers after they were hit with the largest fare rise in five years on the first working day of 2018.
The cost of train tickets have risen by an average of 3.4% with many season tickets increasing by more than £100.
Chris Grayling said that he is "moving as fast as I can" to move fares onto a lower rate of inflation but emphasised that the UK had the biggest investment programme "for decades".
He told ITV News: "Part of the cost of meeting that big investment programme has to inevitably come from fare payers but they are going to get a much better service in return."
- Video report by ITV News Consumer Editor Chris Choi
Mr Grayling had been accused of "shirking the issue" by shadow transport secretary Andy McDonald and the unions for being on a two-day visit to Qatar as rail passengers are hit with the increase.
Speaking from Qatar he said: "I make no apology for being one of a few ministers trying to win business for Britain around the world."
When asked whether he believed it was right to fly business class to Qatar while Britons face fare hikes, he added: "My job is to win business for Britain and that's what I'm doing. I'm not going to get into travel arrangements."
Protests were held outside around 40 stations with members of the Rail, Maritime and Transport (RMT) union handing out chocolates to "sweeten the bitter pill" of the price increase.
Labour claim fares have risen three times faster than wages since the Tories entered office as the dominant coalition power in 2010.
Which routes in the UK have notable increases?
Average season tickets into London terminals have gone up by £146 this year, compared with £74 last January, according to the Campaign for Better Transport (CBT).
Campaigners call for fares to be frozen like fuel
CBT chief executive Stephen Joseph accused the Government of choosing to "snub rail passengers" by continuing to raise fares while fuel duty is frozen for a seventh consecutive year.
"The extra money that season ticket holders will have to fork out this year is almost as much as drivers will save,” Joseph said.
"That doesn't seem fair to us or the millions of people who commute by train, especially as wages continue to stagnate. What's good enough for motorists should be good enough for rail passengers."
The price hike - the largest since 2013 - was determined by the government using last July's Retail Prices Index measure of inflation to determine fares.
Bruce Williamson, of campaign group Railfuture, said "people are being priced out of getting to work" and called for for the Consumer Price Index inflation measure to be used for regulated fare increases.
The CPI is usually lower than the RPI, and is used by the Government to set increases in benefits and pensions.
"If CPI had been used instead of RPI since 2004, then rail fares would be 17% lower, a significant amount of money for season ticket holders who are spending thousands of pounds to get to work,” Williamson said.
"It's no wonder that poor value for money is the number one concern of rail travellers, with British rail fares amongst the most expensive in Europe."
Labour blame price rises on Tories
Labour said commuters are paying almost £700 more a year for season tickets than when the Tories entered office eight years ago.
Shadow transport secretary Andy McDonald said fares had risen three times faster than wages during the period.
"The Tories' failure on our railways means passengers have faced truly staggering fare rises of over £2,500 since 2010," McDonald said.
"Commuters have repeatedly been told that higher fares are necessary to fund investment, but promised investment has been cancelled and essential works have been delayed by years.
"Decisions taken by government ministers are making rail travel unaffordable for the many in favour of huge profits for the few.
"The truth is that our fragmented, privatised railway drives up costs and leaves passengers paying more for less."
What is the government's response?
A Department for Transport spokesman said: "We are investing in the biggest modernisation of our railways since the Victorian times to improve services for passengers - providing faster and better, more comfortable trains with extra seats.
"This includes the first trains running through London on the Crossrail project, an entirely new Thameslink rail service and continuing work on the transformative Great North Rail Project.
"We keep fare prices under constant review and the price rises for this year are capped in line with inflation, with 97p out of every £1 paid going back into the railway."