President Obama called on Iran Friday to release U.S. citizens, including Iranian-American pastor Saeed Abedini, believed to be in Tehran's custody.

As Iran celebrates Nowruz holiday, Obama said that "at this time of renewal, compassion and understanding, I reiterate my commitment to bringing our citizens home."

Three U.S. citizens - Saeed Abedini, Amir Hekmati and Jason Rezaian - are believed to be in prison; a fourth - Robert Levinson - is missing and was last seen in Iran.

"The spirit of family is deeply woven into all of the rich cultural traditions of the Nowruz holiday," Obama said in his statement. "It is a time for reuniting and rejoicing with loved ones and sharing hopes for the new year."

Obama gave the descriptions of the four missing Americans:

• "Saeed Abedini of Boise has spent 2½ years detained in Iran on charges related to his religious beliefs. He must be returned to his wife and two young children, who needlessly continue to grow up without their father."
• "Amir Hekmati of Flint, Mich., has been imprisoned in Iran on false espionage charges for over 3½ years. His family, including his father, who is gravely ill, has borne the pain of Amir's absence for far too long."
• "Jason Rezaian of Marin County, Calif., an Iranian government credentialed reporter for The Washington Post, has been unjustly held in Iran for nearly eight months on vague charges. It is especially painful that on a holiday centered on ridding one's self of the difficulties of the past year, Jason's mother and family will continue to carry the heavy burden of concern regarding Jason's health and well-being into the new year."

"And finally," the president wrote, "we recently marked yet another anniversary since Robert Levinson went missing on Kish Island. His family has now endured the hardship of his disappearance for over eight years." 

Earlier this week, Saeed gave the birthday letter for his son, Jacob, to one of his family members in Iran who was permitted to visit him in prison this week, according to American Center for Law and Justice.

"I saw your beautiful birthday invitation that you had made me and I know how much you want me to be there on your birthday," the 34 year old husband and father wrote. "Daddy loves you so much. I long to be there for your birthday and to make this reunion happen, but my chains are keeping me from you."

Pastor Saeed added that it "breaks my heart as your father" that he won't be there for Jacob's birthday, "but I know the One who is there on your birthday who is there for you and cares for you more than anyone could imagine."

He concluded the letter with a very special invitation, writing, "on this special day, I want you to accept this gift of salvation," urging him to invite Jesus into his heart "as you have invited me to your birthday."

"So happy birthday to my big boy and my hero, Jacob Cyrus Abedini," he wrote.

Pastor Saeed, who is serving an eight year prison sentence for "threatening the security of the state," was first arrested in 2009 while working as a Christian leader and community organizer in Iran's underground home church communities for Christian converts who are denied the right to worship freely in public churches.

Although he was initially released after pledging to stop formally organizing house churches in Iran, he was imprisoned again after returning to Iran in 2012 to help build a state-run, secular orphanage.

The ACLJ notes that Pastor Saeed remains in an incredibly dangerous situation due to the frequent executions, inmate violence and beatings that take place in Iranian prisons. The pastor has suffered long stints in solitary confinement, and beatings and torture at the hands of his jailers and fellow inmates. He was also denied medical attention for his injuries.

As previously reported by the Gospel Herald, the Pastor Saeed's future remains uncertain as six of his fellow prisoners were executed around him last week.

"Saeed was quite shaken as he had to witness 6 fellow prisoners being beaten and taken to be executed (hanged) that day," Pastor Saeed's wife, Naghmeh, was quoted as saying in a report by American Center for Law and Justice on Saturday.

"It was a hard and dark day having witnessed that and seeing life being taken. The prison visit was also very hard as the families of those who were executed were crying and wailing," she added.

Earlier this week, ACLJ Chief Counsel Jay Sekulow testified this week before the U.S. Senate on Saeed's case. The AFP reports that in response, Ambassador at Large for International Religious Freedom, David Saperstein, told him the State Department remains committed to bring the pastor home.

Last month, U.S. President Barack Obama visited Naghmeh, emphasizing that Pastor Saeed's freedom is a "top priority" for him and his Administration.

After the meeting, Naghmeh said the President's words left her with a "renewed sense of hope."

"Pastor Saeed has become the face of the persecuted Christian church worldwide, one of many Christians around the world who face imprisonment, beatings and even death for their faith," said Jordan Sekulow, ACLJ executive director.

"As the world's eye turns to violence against Christians in the Middle East, we raise a united voice in urging Iran to free pastor Saeed and grant him clemency. It's time for Saeed to come home."

Although the pastor was sentenced for endangering "national security," but the ACLJ believes the punishment has more to do with Saeed's Christian faith.