Messi has been widely criticised for his performances in recent weeks with Barca’s hopes of silverware taking a major hit.
The four-time Ballon d’Or winner was a peripheral figure as the Catalans lost 2-1 to Di Maria’s Real Madrid in the Copa del Rey final on Wednesday night.
That showing came on the back of below-par performances in defeats to Atletico Madrid and Granada as Barca crashed out of the Champions League and lost ground in the race for La Liga.
He told Radio America: “Messi is calm. He’s not in a bad moment but the opposition have controlled him very well.
“The problem is that the press always take it out on Messi even when the whole team don’t play well.”
In contrast, Di Maria is enjoying his finest period in a Madrid shirt and continued his recent form by scoring the opening goal against Barca at the Mestalla.
“It’s my best moment since I arrived at Real Madrid,” he said.
“It would be beautiful to win my first Champions League.”
Madrid host reigning European champions Bayern Munich in the first-leg of their Champions League semi-final clash on Wednesday night.