Nastase was sent off for using foul and abuse language as he swore at Johanna Konta and coach Anne Keothavong during the former's Fed Cup match against Sorana Cirstea.
Konta was reduced to tears by Nastase's abuse and the match was suspended.
However, when play resumed on Sunday he tried to enter the arena only to be told he was not allowed in.
The ITF then released a statement confirming that he had been provisionally suspended.
The statement read: "The ITF's Internal Adjudication Panel has issued Ilie Nastase with a provisional suspension under the Fed Cup Regulations for a breach of the Fed Cup Welfare Policy at the Fed Cup by BNP Paribas tie in Constana.
"Under the terms of the provisional suspension, Nastase may not participate in the Fed Cup in any capacity with immediate effect, and shall be denied access to, accreditation for, any ITF event including Fed Cup.
"The investigation by the Internal Adjudication Panel is ongoing. No further comment will be made during the investigation."
Read the original article on Eurosport: Nastase suspended by ITF