"We believe that the 12 executions were an isolated incident and not part of a strategy to destabilize the state," Guzman told reporters.
A top Mexican public security official who visited Merida recently had noted that the city had remained largely untouched by the drug war that has left more than 2,600 dead in Mexico so far this year.
Mexicans plan nationwide mass protests on Saturday, in which they will dress in white and carry only candles, in a bid to force the government to act over a spike in murders, kidnappings and police corruption.
Rights and religious groups, kidnap victims and citizens plan to march down major avenues in towns and cities across the country.
The planned protests come amid daily reports of murders and massacres, particularly in the northern Chihuahua State, which has the highest murder rate in the country and where drug cartels are fighting a turf war for control of key drug routes to the United States.
Violence has escalated throughout Mexico since Felipe Calderon, the Mexican president who took office at the end of 2006, launched a crackdown on drug trafficking that included deploying more than 36,000 soldiers across the country.
Some 2,700 people have died this year in gangland-style killings, more than in all of 2007, according to national media and Mexico has overtaken Colombia and Iraq with its kidnapping record.