"We are cautiously optimistic," said team boss Toto Wolff. "Perhaps more optimistic than cautious at the moment!"
Briton Hamilton currently has the upper hand, having won four of the five grands prix so far and finally taking the championship lead from Rosberg in Spain.
Some believe it is a major psychological blow for the German.
"Break me down mentally?" Rosberg hit back when asked if Hamilton's superiority is getting to him.
"I think he will struggle with that one."
Hamilton, six months older than Rosberg, is often credited as perhaps the naturally fastest driver on the F1 grid, while it is said that Rosberg's speed is more analytically crafted.
"They are different characters," Wolff told the APA news agency.
"Lewis has instinct and merciless speed," said the Austrian. "Nico's preparation is meticulous. He has a great understanding of the car and is fascinated by the data."
But Wolff said Hamilton also does not neglect the hard work off-track.
"He has become an incredibly hard worker," he said. "This year even more than last. I think everything has now taken a higher priority."
However, Wolff said Hamilton's character has another side.
"He is incredibly sensitive to criticism," he explained, "with strong reactions. But this is also why he drives as he does."
Team chairman Niki Lauda said after Hamilton's Barcelona win that the 29-year-old Briton is currently "unbeatable".
Earlier, 1992 world champion Nigel Mansell hailed Hamilton's 2014 form as "close to perfection".
Rosberg replied: "Lewis is just a human, with strengths and weaknesses. And I know what I can do."
Some predict that Hamilton's advantage may eventually get to Rosberg, but Wolff is not so sure.
"He (Rosberg) has no problem dealing with the situation," Wolff is quoted by Speed Week.
"Of course he is disappointed to finish second behind his teammate, but I have no doubt that they will both have their triumphs against one another," he added.