Alex Salmond left the first day of the SNP annual conference in Perth for the discussions in Edinburgh.
"Governments can't make agreements" in such disputes but can "encourage the circumstances in which agreements can be found", he told party delegates.
Both negotiation and co-operation are necessary for the situation to be resolved, he said.
Mr Salmond announced he would host the talks as he addressed SNP activists at the start of the party conference, saying that the Grangemouth dispute is a "difficult industrial situation" and that he is disappointed that talks at the conciliation service Acas failed to resolve it.
"We worked really hard with others to get the company and unions into Acas on Monday," the First Minister said.
"We were pleased we succeeded in persuading them to go, we were disappointed there wasn't an effective resolution.
"Governments can't make agreements. We can encourage agreements but we can't make agreements. But we can encourage the circumstances in which agreements can be found."
Grangemouth owners Ineos said it is keeping the plant shut while workers are consulted about proposed changes to issues such as pensions.
The dispute over the treatment of union convener Stephen Deans has cost Ineos £20 million at a time when the refinery is losing £10 million a month, according to the company.
Workers have now been given details of Ineos's survival plan, with the firm saying it is D Day for the oil refinery site.
Unite, which called off a 48-hour strike planned for Sunday, accused Ineos of ''fancy accounting manoeuvres'' and challenged the firm's claims about the financial difficulty it faces.
Mr Salmond said contingency plans to cover the period when the plant is shut are "well laid to ensure the flow of petrol and fuel continues and the Scottish economy continues to function".
Letters have been sent to the homes of Grangemouth workers detailing changes to their terms and conditions, including ending their final salary pension scheme, freezing pay and bonuses, reducing shift allowances and new agreements with unions including having part-time conveners.
The letter said: "We expect to seek individual employee agreement to the final changes, and, where agreement is not forthcoming, to implement the changes in due course by issuing notices of termination and offering new contracts of employment to those employees which incorporate the new terms."
Unite said staff have been told to accept the new terms and conditions by 6pm on Monday, which amounts to a "sign or be sacked" ultimatum, and that it is considering legal action.
Scottish secretary Pat Rafferty said: "This is cynical blackmail from a company that is putting a gun to the heads of its loyal workforce to slash pay, pensions and jobs. We are considering taking legal action over the company's menacing tactics and urge members not to be threatened into signing their livelihoods away.
"It is increasingly clear that the company is deliberately generating a dispute and hiding behind fancy accounting to attack its own workforce. We will not allow such an important national asset to be held to ransom and urge Ineos to drop the blackmail and engage meaningfully with the workforce over a transitional agreement."
Ineos said it is going directly to the employees rather than deal with their union, amid fresh clashes over the company's finances and its decision to close the plant.
Ineos chairman Calum MacLean said: "This is D Day for Grangemouth. The site is safely closed whilst we consult the workforce. If we can get the changes we want, the company has committed to investing a further £300 million in the site which will help secure its long-term survival.
"The shareholders have expressed extreme concern that the industrial action over recent days has cost the site £20 million at a time when losses are already £10 million per month. The site cannot afford this, hence the urgent need for employees to decide to support the company.
"We are going to give our employees a few days over the weekend to reflect on our proposals and then get their feedback. This feedback will be critical in influencing the shareholders in their decisions about what to do next."
The Grangemouth refining and chemicals complex has been shut down twice in the last 40 years: during a previous strike in 2008 and again in preparation for the latest walkout, according to Ineos.
It said it is unable to restart the complex on safety grounds.
"The Grangemouth site is three times the size of the city of London and it is an incredibly complex system of manufacturing plants all connected by miles of pipes carrying highly flammable materials. Shutting down the site and restarting again is not like switching the lights off and on. It takes days to shut down properly and it takes weeks to bring it back up again," a statement from the firm said.
Mr Deans, the trade union convener, was involved in the row over the selection of a Labour candidate in Falkirk where he is chairman of the constituency party.
He was suspended by Ineos and later reinstated but is facing an internal investigation by the company over the affair.