Walid Moallem said the deal was approved at the league's headquarters in Cairo Monday.
"We wouldn't have signed the Arab protocol if it did not preserve the Syrian sovereignty," al-Arabiya quoted Moallem as saying in Damascus.
The foreign minister said Russia had asked Syria to sign the protocol and allow observers in.
"It is up to the Arab League to remove sanctions against Syria," he said.
Moallem said the league agreed to make a number of amendments to the deal at Syria's request, The Irish Examiner reported.
For months, the 22-member Arab League threatened Syria with action if it fails to halt the violence that has left more than 5,000 people dead since anti-government protests began in March.
On Nov. 27, the league agreed to suspend Syria from its meetings and also approved an array of sanctions against the country after it refused to adhere to requests to permit monitors to visit and take steps to curb the violence.
Syria ignored ultimatums set by the league and instead issued a number of conditions, including the lifting of sanctions, before it agreed to allow monitors in, Naharnet.com said.