The co-convener was speaking outside Glasgow University this morning as he launched his campaign to win the Glasgow North constituency at the poll on June 8.
The Greens have faced heavy criticism from opponents this week following the announcement that it would stand in just one seat in Glasgow, Falkirk and Edinburgh - with the Tories accusing them of helping to prop up the SNP vote.
Harvie insisted the decision was made by local party branches and was largely down to a lack of funding.
But the lack of candidates means the Greens are not eligible for a party broadcast on STV - although they will still appear on a BBC election debate.
He said: “Our local branches make their own decisions and most of our local branches have decided they’ve put their energy, time and money into the local election campaigns this year and they’re not in a position to run in every constituency.
“I regret the fact that there will be many Green voters who know that they don’t have a Green candidate this year.
“I regret that and if we had the kind of resources that other parties seem to take for granted, we would be able to do that.”
He added: “(In 2015) we had been able to build up our electoral reserves and we had time to prepare for it.
“I think the contempt that Theresa May showed to local democracy by calling a Westminster election right in the middle of a local election is appalling.
“I’m not going to make any bones about it, the Greens cannot go knocking on doors of millionaires and billionaires asking them to fill our coffers at the drop of a hat.
“By necessity, we need to focus our efforts, and that’s what we’re going to do.”
Two years ago the SNP won a large majority in Glasgow North but Mr Harvie is confident of becoming the first Scottish Green MP after positive local election results in the city for his party.
The only other Green candidates standing are Lorna Slater in Edinburgh North and Leith and Debra Pickering in Falkirk, but Mr Harvie refused to back any other parties in other areas.
“We will not endorse any other party, I will certainly not endorse any other candidate,” he said.
“The advice I would give to anyone who doesn’t have a Green candidate to vote for is ask yourself what are the most important issues to you, then put them to the candidates and judge them as individuals.”
Despite describing some aspects of Westminster as “archaic and antique”, Mr Harvie said it is important for more Green voices to be heard as powers are transferred back from the European Union.
“I think if this was about personal self interest, Holyrood is probably a much more fun place to work,” the party co-convener said.
“There’s a great deal wrong with the Westminster political culture, with its institution, with the political system there, and from the experience of my colleague Caroline Lucas she’s had a very mixed experience over the last few years.
“I am absolutely committed to advancing Green politics in this country and I believe passionately that Scotland and Glasgow needs a Green voice at Westminster.
“When all of those regulations protecting our social and environmental well-being are being transferred from Europe to Westminster, I’m not willing to leave those in the hands of a right-wing Tory government that wants a bonfire of the regulations.”