The group had returned to Khartoum Bahri Evangelical Church's training school in the capital on Friday - breaking locks to enter - after being asked by security officials earlier in the day - without prior notice - to leave the building immediately.
The building had been involved in a long-running dispute with an illegally-convened rival church committee which has been backed by the government and it is thought the illegal committee wants control of the training school so it can be sold or rented.
One person was convicted of "obstructing the police" and "breaching the public peace" and ordered to pay a fine of 500 Sudanese Pounds (around US$82), while the rest of the group was convicted of "obstructing the police" and ordered to pay a fine of 300 Sudanese Pounds (around US$49) each.
The group, which must pay a total around £545, was released immediately following the trial on Sunday
Dr Khataza Gondwe the Africa and Middle East Team Leader for the anti-persecution organisation, Christian Solidarity Worldwide, said: "We are deeply concerned by these convictions, which amount to official restrictions on the right to peaceful assembly, as articulated in article 21 of the International Covenant on Civil and Political Rights, to which Sudan is party.
"We urge the Sudanese government to end its campaign of harassment and interference in church affairs, to ensure these convictions are overturned and to uphold its obligations under international law to promote, respect and protect the rights to freedom of religion or belief and to peaceful assembly."
CSW, is warning Christians in Khartoum "are facing a campaign of repression that seems designed to pressurise them into leaving the country."
Speaking before the convictions, Dr Khataza Gondwe said: "The continued refusal by the Ministry of Religious Endowments and Guidance to recognise the church's legitimate land and buildings committee is further indication of an ongoing campaign of harassment and an unwarranted interference in church affairs.
"We urge the international community, in particular the African Union, to hold Sudan to its international obligations, including its undertakings to promote, respect and protect the right to freedom of religion or belief and the rights to freedom of association and assembly, as articulated in articles 8, 10 and 11 of the African Charter on People's and Human Rights."