If there is collision between the president and Congress, can Congress restrain the president in foreign policy making?
It's very difficult, but sometimes Congress can influence the president on foreign policy. This website goes into a lot of details about the ways the Congress and the Executive branch conduct foreign policy.
One of the key phrases is:
"In nearly all of these circumstances, Congress can either support the President's approach or seek to change it. In the case of independent Presidential action, it may be very difficult to change policy in the short term;. . ."
Be sure to study this section near the bottom of the report "Legislative Restrictions/Funding Denials."
Congress does have a major influence on foreign affairs. This is part of our checks and balances system.
1. Congress appropriates the money for the armed forces, foreign aide and the running of our embassies in foreign countries. They can reduce or eliminate the Presidential requests for funds. Just think about Congress giving funds for our war in Iraq.
It was said that Theodore Roosevelt wanted to send the American fleet around the world to show off US power. Congress refused to grant him the necessary money. Roosevelt stated that he had enough money to send the fleet halfway around the world and would leave them there. Congress granted the money,
2. All treaties must be approves by the Senate by a 2/3 vote although executive agreements need not be approved.
2. The Senate has to approve all major appointments by a 2/3 vote as well. This includes the Security of State who is in charge of our foreign policy and the major heads of our armed forces.
3. The President need to obtain the consent of Congress to send our armed forces out of the country for more than a certain number of days.
The other part of the equation which you did not ask about is how the President may curtail Congress although one part of that answer was given above.