In a video recorded on a mobile phone on his plane the presumptive Republican nominee commits to working hard to gain votes.
The message was recorded for the start of the National Hispanic Christian Leadership Conference.
"National Hispanic Christians - three great words," says Mr Trump.
"We are going to take care of you, we are going to work with you, you are going to be very happy, you are going to like president Trump," he adds.
More than one thousand Christian leaders will attend the conference in California.
Polls show Trump is far behind his expected Democrat rival Hilary Clinton for Hispanic votes.
Samuel Rodriguez, president of the National Hispanic Christian Leadership Conference, told Fox News: "Can Donald Trump redeem the narrative? I'm a pastor. I do believe in miracles but, boy, this would be a miracle."
Earlier this year the Pope questioned the Christianity of Trump.
During a press conference Francis referred to Trump's plans to build a wall between the United States and Mexico if he wins November's election.
"A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian," the pontiff said.
"This is not in the gospel," he stressed.