Business Secretary Greg Clark has met Peugeot boss Carlos Tavares discuss its potential takeover of Vauxhall from General Motors.
The Government has been seeking assurances over the 3,400 people that work at Vauxhall's plants at Ellesmere Port and Luton.
Speaking after the meeting, Mr Clark said his discussions with the Group chief executive had been "very constructive and reassuring".
"I made the case for how important Vauxhall is to the UK, how important its plants and its other employees are across the country and how successful it's been," he added.
Mr Clark said Mr Tavares wanted to expand construction and "was not here to close down our plants".
Ellesmere Port has agreements in place to build the Vauxhall Astra until 2021, while the Luton plant is under contract to manufacture the Vauxhall Vivaro van until 2025.
The business secretary said Mr Tavares assured him "the commitments would be honoured to the plants that we have here and that his ambition was to increase market share".
"We also talked about how important it is that Vauxhall pensioners are well treated and that was fully recognised as well," he added.
"Clearly no deal has been done, discussions are continuing but it was I think a constructive conversation," Mr Clark stressed.
He added that they had agreed to keep in "close touch".
Len McCluskey, Unite's general secretary, also met with Mr Tavares on Friday and said their discussion had been "open and relatively positive".
Mr McCluskey said the executive was "very pro-union" and said he came away from the meeting without his "optimism being dented".