John Swinney has said the pilot scheme to scrap peak rail fares has been “very effective” but noted that “everything has to be paid for”.
He was responding to calls from the Scottish Greens, who are now an opposition party, for the scheme to be made permanent.
The scrapping of peak prices began in October last year and was recently extended to the end of June, with the Scottish Government due to make a decision on whether it will continue further.
Mr Swinney spoke to journalists just after he had been sworn in as First Minister at the Court of Session in Edinburgh, ahead of his journey to Bute House to appoint his cabinet.
Mr Swinney said: “What I’m pledging myself to do is to is to engage constructively with other parties on (their) priorities to make sure we can reach conclusions that can be supported in Parliament.
“I have to be mindful of the fact that everything has to be paid for. The peak rail fares pilot has been a very, very good measure.
“It’s been very effective. We obviously have to look at the resources involved in supporting that on a permanent basis.”
He said this kind of issue would be at the “core” of dialogue with other parties.
Earlier, the Scottish Greens said peak rail fares were an “unfair tax” on workers and students.
When previous first minister Humza Yousaf brought the powersharing deal with the Greens to an end, they withdrew their confidence in him and he resigned days later.
This set events in motion which led to Mr Swinney emerging as the sole candidate for SNP leader and First Minister.
Green MSP Mark Ruskell said: “By making the scheme permanent we can ensure that even more people are able to feel its benefits and change their long-standing habits.
“The best changes are ones that help our climate and our communities while supporting household budgets, which is exactly what happens when we cut the cost of transport.”
He added: “Peak rail fares are an unfair tax on the many workers and students who do not have any choice about when they start work or go to study, that is why the Scottish Greens agreed with ministers to deliver the pilot scheme.
“During our time in Government, the Scottish Greens strongly supported the move to bring ScotRail back into public ownership.
“We must now put that to good use and ensure our rail network delivers for people and planet.”