His Movement for Democratic Change (MDC) party formed a unity government with President Robert Mugabe’s ZANU-PF in February, raising hopes that a deep economic crisis and political hostilities would come to an end.
But the former trade unionist said being in a coalition government had its frustrating moments, including the slow pace of media and political reforms which were, however, on course.
"The limitations (in a coalition) are not a result of lack of commitment, but a result of the limitations you find in a marriage of convenience," Tsvangirai told MDC members attending an annual conference.
"We have not moved as far and as fast with positive changes as the people demand and deserve."
While Tsvangirai and Mugabe had cleared all outstanding issues in the government, they bitterly disagree on the appointments of the central bank governor and attorney general, all Mugabe allies.
Tsvangirai said failure to quickly resolve the disagreements would make it difficult for the government to convince Western powers to release badly needed funding to restore Zimbabwe’s once vibrant economy.
Tsvangirai urged the international community on Friday to fully engage Zimbabwe, as shunning it would only bolster hardline elements opposed to the new political arrangement.
Formed in 1999, the MDC was the biggest opposition party in the country and in its first election in 2000 came close to dislodging ZANU-PF from power.
The party repeatedly accused ZANU-PF of electoral violence and fraud and in March last year Tsvangirai handed Mugabe his first defeat in a presidential and parliamentary vote, only for the 85-year-old leader to return to power after a one-man run-off marked by violence.
Tsvangirai said that although schools and hospitals had opened, goods were available and prices had stabilised, the country had opened up to aid agencies and the constitutional making process had started, much remained to be done.
"We have not yet succeeded in restoring the rule of law, that our people do not live from fear, hunger and poverty, that our state media remains partisan and prejudiced, that freedom of association is not yet a right that all can enjoy," he said.