Washington — President Reagan is tightening the screws on Nicaragua. At the same time, the search for a negotiated peace in Central America is intensifying.
According to a top State Department official, Mr. Reagan's current approach combines ''a lot more carrot and a lot more stick,'' but without much coordination between the two.
Another administration official says the carrot-and-stick analogy is much too simplistic and that it tends to overlook Reagan's search for a bipartisan consensus on Central America in the United States Congress.
But with speculation about a possible US naval quarantine of Nicaragua swirling around Washington, Democratic critics in Congress charge that the stick is much more in evidence than the carrot.
The stick consists of the use of force as well as the threat of force. The administration says its aim is to stop the flow of arms from Nicaragua to El Salvador and cause the Nicaraguan government to fulfill pledges made to build a democratic system.
The President is reported to have plans to increase that force through more money for the guerrillas fighting Nicaragua's Sandinista government. Based in Honduras, the guerrillas have vowed to increase their attacks and to drive deeper into Nicaragua.
The threat of force comes from the aircraft carrier Ranger, which President Reagan has diverted to Pacific waters off Central America. This may be followed next month by joint exercises conducted by Honduran forces and US Army, Navy, and Air Force units. In addition, American naval exercises are planned in the Caribbean. Administration spokesmen contend that all these qualify as ''routine'' exercises intended to show US interest and capabilities in the region. But the exercises are apparently to be larger in size than any in the past.
Meanwhile, Israel is reported to be adding to the stick by offering new weapons to the anti-Sandinista guerrillas based in Honduras. State Department officials say, however, that the US didn't solicit the aid from Israel, even if it is appreciated. Israeli aid would provide fallback support for the guerrillas should Congress at some point cut off American support.
The conciliatory part of the approach consists of a new trip to Central America by Richard Stone, Reagan's envoy to the region, a heavily qualified US welcome for a Nicaraguan peace signal, and intensified State Department interest in the latest proposal from the so-called Contadora nations (Mexico, Venezuela, Colombia, and Panama).
While in Panama City on Saturday, Ambassador Stone denied charges that the US was using the Contadora group as a smoke screen to gain time for military intervention in the region. Stone was apparently still seeking a meeting with representatives of El Salvador's leftist-led guerrilla groups.
''It's the old tough cop, nice cop routine,'' says Harvey Summ, director of Latin American studies at Georgetown University, describing Reagan's use of force and the threat of force, combined with negotiating offers. ''This is the essence of diplomacy.''
But Rep. William V. Alexander (D) of Arkansas, chief deputy House majority whip, charges that Reagan's approach amounts to traditional gunboat diplomacy.
''This administration believes that force and the use of coercion is the proper way to deal with the situation,'' said Mr. Alexander in an interview. ''This is the Big Stick diplomacy of Teddy Roosevelt revisited.''
''The underlying premise is that the peoples of Latin America do not have the judgment to govern themselves,'' he says, adding that the administration ''is incapable of coordinating the carrot and stick. It doesn't understand the problem. The problem is not Nicaragua. It's 500 years of injustice, poverty, and hunger.
''The Reagan administration is implementing war plans in Central America. This is not just a policy of intimidation. If this doesn't stop, we will see thousands of American troops in Central America by the end of the year.''
Alexander who has made himself something of an expert on the Contadora process, recommends that Reagan call for a Central Amercian cease-fire and a conference of nations concerned, and then take the first step by halting US arms shipments to El Salvador. Then, together with the Contadora nations, a plan of action should be drawn up, he says, followed by a call to the United Nations for peacekeeping assistance.