Agriculture Secretary John R. Block yesterday promised to help America's farmers through their immediate short-term debt crisis, but said the solution to the long-term farm problem is to scale back government's role and let market forces prevail.

Speaking on NBC-TV's "Meet the Press," Block said the only alternative to an orderly phasing-out of government farm-support programs would be an "even more heavy-handed" federal role, with the government supervising "an acreage-reduction plan" and deciding which farmers must leave the business.

"The time is right to start moving the government out of agriculture," Block said. Although acknowledging that the government is "never going to get completely out," he said, "We must move the government more out than it's been before."

But Block emphasized that his long-term plan to reduce the federal role in farming would not stop the Reagan administration from providing short-term relief, in terms of direct and federally backed loans, to help the financially strapped farmers in time for next month's spring planting.

Block's comments came a day after Senate Democrats ended a filibuster to force action on an emergency farm bailout plan, and as the nation's governors gathered in Washington for a parley in which the farm crisis, and the administration's farm-support restructuring plan, received a high priority.

Appearing on the same program, South Dakota Gov. William Janklow (R), who is leading his state's 105-member legislature in a massive Capitol Hill lobbying campaign, blamed Office of Management and Budget Director David A. Stockman for the level of rhetoric about farm aid.

"This farmer-bashing that he's gone through the last few weeks . . . absolutely has no place in the discussion," Janklow said. "I think the level of rhetoric of the problem has been created as much by David Stockman as anybody else."

Janklow said that he wanted to meet Tuesday with President Reagan, but that the president is unavailable. His delegation is to meet instead with Vice President Bush.

Janklow blamed the farmers' plight on record-high federal budget deficits, which he said had raised interest rates and strengthened the dollar to the point where American farm-exports were stifled. "The farmers' greatest enemy is the Congress of the United States," he said, "because they don't have the guts or the courage and they won't make the hard decisions to straighten out America's fiscal mess."

But Block said the problem is decades of federal farm-support programs, which he said "forced many farmers to become more dependent . . . than they liked to be."