Radnor told Collider that the sitcom's cast are in "such a confusing place", since they are uncertain if the show's upcoming eighth run will be its last.
"None of us know if the show is going to be ending this year or not," he admitted. "I think the writers really need to know more than we need to know because they need to start either wrapping things up or keeping the story going.
"The studio has only recently engaged us in talks about it, so when we were asked about it, we really had nothing to report because no-one had come to us yet."
Radnor went on to say that he would not turn down another season of How I Met Your Mother if an "attractive" offer was made.
"If a deal could be struck for everyone... including the writers to keep going, then we'll see what happens," he said.
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The 38-year-old also voiced his desire to end the comedy - which began in 2005 - on a satisfactory note for fans.
"There's such a high degree of investment in the show, that I think it would be a real shame if it was wrapped up in anything other than the most elegant fashion," he admitted.
How I Met Your Mother's eighth season begins on Monday, September 24 at 8/7c on CBS. In the UK, the series airs on E4.
Watch the cast of How I Met Your Mother discuss the new season below: