Gordon Martin, the union’s regional organiser in Scotland, said “cool heads and brave hearts” are needed to resolve the dispute – which has impacted rail services across the UK since June last year.
As RMT members again staged strike action on Wednesday, with more planned this week, he called for UK ministers to “intervene in a positive manner”.
Scottish First Minister Nicola Sturgeon has already urged the UK Transport Secretary to “intervene immediately” in a bid to end the row over pay and conditions.
Mr Martin said that while there have been “warm words” from Transport Secretary Mark Harper, there have been “bad actions” from the UK Government, claiming ministers are seeking to impose conditions the RMT “cannot and will not accept”, including driver-only operation on trains, the closure of booking offices and cuts to maintenance schedules.
He said: “What we’re looking for is cool heads and brave hearts, sit round the table and properly negotiate, not just try and ram through the wish-list of the UK Government, because our members will not accept that.”
Speaking on BBC Radio Scotland’s Good Morning Scotland programme, he continued: “The men and women we represent are very keen to be back at work serving the public, rather than standing on picket lines fighting for a fair offer.
“But the members know what is at stake – their jobs, their terms and conditions and the safety of the travelling public.
“We have had some warm words from the latest Transport Secretary but we need those warm words to go into action, and we need action on the real concerns.
“We need ministerial involvement, we need decision makers to be in the room, because we’ve had offers on the table that have then been taken off the table through UK Government intervention.
“We need them to intervene in a positive manner, not a negative manner, and let’s get this sorted and get people back to work.”
During this latest phase of the dispute – with strike action on January 3, 4, 6 and 7 – ScotRail is only able to run services on 12 routes across the central belt, Fife, and the Borders between 7.30am and 6.30pm.
David Simpson, ScotRail service delivery director, said: “It’s really disappointing to see more widespread disruption across the whole Great Britain rail network as a result of the dispute between Network Rail and the RMT at a time when we need to be encouraging more people back to the railway.
“For ScotRail, it’s going to mean that we won’t be able to operate the vast majority of our services between 3 and 7 January, which we know will be really frustrating for our customers.”
Liam Sumpter, route director for Network Rail Scotland, said previously: “We understand the impact this strike will have and we are working hard to keep as many passengers as possible moving during the next phase of RMT industrial action.
“We remain committed to working with the RMT to find a solution to this dispute, but we also need to agree a deal that is fair on the taxpayers who fund our railway.”