The Romania defender moved to Upton Park on a free transfer this summer after his contract at Shakhtar Donetsk expired but Sam Allardyce has told him he will not be rushed into the first team.
"In principle, West Ham finished the last season well," said Rat.
"The manager decided to leave Joey O'Brien on the left flank in the opening games of this league season.
"Even before the start of the season Sam Allardyce told me that he would not field me in the starting line-up straightaway.
"This is normal. He wanted me to feel the atmosphere of the English Premier League - it's a new league for me and a totally different level.
"The coach explained to me that I should first get a feel for the English Premier League, and then he will play me."
Meanwhile, Sam Allardyce was delighted with a 1-0 friendly victory over Espanyol on Thursday night, with Mark Noble scoring the decisive penalty.
"It was an excellent game," he told the club's website.
"It's a different way to play when you're away in Europe. It's not like the Premier League where it gets frantic and high tempo all the time.
"We played the game out really well, and with no injuries too, which is the most important thing. It's a very good workout and it's given the young boys a real experience.
"For the senior players too - James Tomkins, Adrian in goal, Matt Taylor - it was important for their match fitness. For the whole squad from the aspect of tactical, technical and fitness it was very, very good.
"It was a worthwhile workout for our players in the international break and now we hope our international players come back without any problems."