Mr Kennedy is leading a major trade delegation currently visiting Northern Ireland.
Speaking in Londonderry, the United States Special Envoy said big investment requires stable government.
"Of course it would be better if there were a government up and running," Mr Kennedy said.
He added: "If you are talking about making investments in the billions of dollars you need to have that political stability.
"We hope that we come to a point quickly that we can get that political stability, itʼs been a message we have heard a number of times from members of our delegation."
On Wednesday night, party leaders met delegates during a dinner at Stormont.
Earlier this year, US President Joe Biden promised the delegation when he visited Northern Ireland.
He said "scores" of US firms wanted to come to Northern Ireland; some already employing over 30,000 people.
The delegation is a blend of US companies already present in Northern Ireland and potential investors.
Some new investment has been announced during the groupʼs visit this week and on Tuesday, the New York State pension fundʼs comptroller, Tom DiNapoli, said it is to invest up to $50m (£41m) in Northern Ireland businesses.
ʼSense of urgencyʼ
Stormont has been without a functioning executive for 20 months as the DUP protests against post-Brexit trade arrangements for Northern Ireland.
In recent weeks both the Northern Ireland Secretary Chris Heaton-Harris and DUP leader Sir Jeffrey Donaldson have hinted at progress being made in talks about Stormontʼs return, however, the impasse continues.
Sir Jeffrey said on Thursday there was still a "distance to travel" before discussions with the government would conclude.
He said he was not embarrassed that the trade visit was happening without a government at Stormont.
"Every process of dialogue reaches a moment where youʼve taken the talking as far as you can and decisions are needed - I think there is still room to move, there is still a distance to travel to get the outcome we need but we are moving in the right direction.
"I canʼt predict if we will get the solution that we need but I will work night and day to get it."
On Wednesday, Mr Heaton-Harris repeated that he believed talks with the DUP are in the "final stages".
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Meanwhile the tanaiste (Irish deputy PM) and foreign affairs minister Micheál Martin said unionists had "missed an opportunity" to claim the Windsor Framework as a win.
The Windsor Framework, which was agreed by the EU and UK in February, is the revised post-Brexit deal for Northern Ireland.
"The Windsor agreement was a major milestone. Actually unionism should have claimed victory. Much of what they campaigned for… the vast majority of that was delivered within it." Mr Martin told BBC News NIʼs The View.
Mr Martin also told the programme he has a good relationship with Northern Ireland Secretary Chris Heaton-Harris but he believes co-operation is not the same as in the Good Friday Agreement era.
Earlier on Thursday, Ulster Unionist Party (UUP) leader Doug Beattie said it is "absolutely embarrassing" that the major trade delegation is visiting Northern Ireland during Stormontʼs suspension.
Mr Beattie was speaking after a business breakfast involving MLAs and the US trade envoy.
Speaking after the business breakfast on Thursday, Mr Beattie said US businesses had raised the issue of political stability with him.
"They did ask when do we get to the stage of politicians being irrelevant? It is embarrassing that we donʼt have a government."
Sinn Féin vice-president Michelle OʼNeill said she felt there was a "sense of urgency" following this weekʼs events.
"The mood music is positive but we need to build on that," she said.
Asked if there was more optimism or pessimism about the chances of Stormont, Alliance Party leader Naomi Long said her optimism was changing on an "hourly basis".
Social Democratic and Labour Party leader Colum Eastwood said "common sense should say this is the time to go back in", and that he was optimistic about the future.