Donald J. Trump, tempering the tone of his hard-line approach to immigration for a general election audience, avoided repeating his previous call for mass deportations on Monday and instead said he wants to come up with a “really fair” plan to address the millions of undocumented immigrants now in the country.

The softer comments from Mr. Trump, who postponed plans to give a major immigration speech this week in Colorado, follow months of vows to build a wall along the Southern United States border with Mexico and deport immigrants who have entered the country illegally. Those proposals were a centerpiece of the platform that helped propel Mr. Trump to winning the Republican presidential nomination, and a shift would be significant.

Asked on Fox News if he was flip-flopping on his immigration ideas, Mr. Trump insisted that he still intends to be “strong” while emphasizing the importance of fairness when it comes to immigrants who came to the United States illegally.

“We want to come up with a really fair, but firm, answer,” Mr. Trump said. “It has to be firm. But we want to come up with something fair.”