The 25-year-old has offers from United as well as current club Swansea, while he is also wanted by League One side Leeds United.
He held talks with Iron manager Nigel Adkins on Thursday, and has been set a deadline of Tuesday to come to a decision over his future.
He has been offered a 12 month deal to stay at the Liberty Arena, but he says he wants a longer contract if he is not to move on.
"My agent is in talks with a number of clubs" Iriekpen told the South Wales Evening Post.
"I have got until June 19 to decide and, of course, I'm still thinking about Swansea. I've been there for the last four years and they have put an offer on the table.
"That offer has not changed, though. It's still one year, so we'll have to see what happens."
Adkins is looking to add two centre-backs to his squad - with Newcastle youngster Phil Cave also reported to be a target.