The restriction meant that the Pilgrims have been unable to make any moves in the January transfer window since it opened last week.
Meanwhile, Argyle have extended the contract of Kari Arnason, keeping the midfielder at the club until 2012.
The Icelander, 27, who originally signed for Plymouth from Danish side Aarhus in July, has played the majority of his football at Home Park in defence.
Head coach Paul Mariner told BBC Sport that securing Arnason's services for another two years is a positive step forward for the club.
"I'm extremely pleased," said Mariner. "Kari's been an integral part of what we've been doing.
Let's see the Board put its money where its mouth is and support Mariner in getting Argyle away from the bottom of the Championship
Cornwallmatt
"I think he's been a a tremendous leader for us on the field as everybody knows."
Arnason has made 17 appearances for Argyle this season, scoring once, during the 4-1 win against Reading on 28 December.
"Kari came as a central midfield player," added Mariner. "And I still think he can do that job.
"He's playing central defence for us at the moment and his consistency at this level has been fantastic."
Plymouth started the New Year off the bottom of the Championship table after successive league wins - and held leaders Newcastle United in Saturday's FA Cup third round tie at Home Park.
Source: BBC Sport
Source: BBC Sport